Millwright Manual PDF (British Columbia)

MN1237 MILLWRIGHT MANUAL Province of British Columbia Ministry of Labour Apprenticeship Branch Second Edition 1996 Canadian Cataloguing in Publication Data Main entry under title: Millwright Manual for the Apprenticeship Branch, Ministry of Labour, Province of British...

MN1237 MILLWRIGHT MANUAL Province of British Columbia Ministry of Labour Apprenticeship Branch Second Edition 1996 Canadian Cataloguing in Publication Data Main entry under title: Millwright Manual for the Apprenticeship Branch, Ministry of Labour, Province of British Columbia. SAFETY ADVISORY Be advised that references to the Workers' Editor: Jenni Gehlbach, Cf. Credits. Compensation Board of British Columbia Previous ed. published: Manual of Instruction for the safety regulations contained within Ihese Millwright Trade I Richard A. Michener. Province of materials do not/may not rellect the most British Columbia Apprenticeship Training Programs recent Occupational Health and Safety Regulation (the current Standards and Branch, 1980. Regulation in Be can be obtained on the ISBN 0-7718-9473-2 following website: http://www.worksafebc.com}. prease nole that it is always the responsibility of any I. Mills and millwork - Handbooks, manuals, etc. person using these materials to inform 2. Milling machinery - Maintenance and repair. him/herself about the OclXlpational Health L Gehlbach, Jenni. II. Michener, Richard A. Manual of and Safely Regulation pertaining to hislher instruction for the millwright trade. 1I1. British area of work, Industry Training and Apprenliceship Columbia. Apprenticeship Branch. Commission August 2001 TJl040.M541996 621.8 C96-960180-8 Ordering Queen's Printer Millwright Manual Government Publication Services Order number: MN 1237 563 Superior Street ISBN: 0-7718-9473-2 PO Box 9452 Sin Prov Govt Victoria, British Columbia Canada V8W 9V7 Telephone: 250387-6409 or 1 800 663-6105 Fax: 250387-1120 Email: [email protected] web: www.publications.gov.bc.ca Payment options are by company cheque or money order (no personal cheques) made payable to Minister of Finance; and Visa or Mastercard, including expiry date. Copyright 1996, Province of British Columbia Ministry of Labour THIS PUBLICATION MAY NOT BE REPRODUCED IN ANY FORM. Technical experts Ernie Janzen Owen Collings Peter Fill Colin Haigh Steve Ramage AI Shehowsky Robert Wereley Review committee it.~_fill:~!~_ _ _ _ _ _ Roger Tremblay John Davies Norm Fair Ian Hodgetts Harold Kirchner Jim Martin Doug Wiebe Project management __'l_ _ _ _ _ _~~.~_ _ _ _ _ _~ British Columbia Institute of Technology Learning Resources Unit Brian Thorn Adrian Waygood Production Editor: Jenni Gehlbach Graphic Artists: Su Gillis Tim Bonham Margaret Kernaghan Kathy Rogers GeorgeTuma Elena Underhill Ken Zupan Production Assistant: Pat Holting Contents Chapter 1 Safety Chapter 2 Trade Science Chapter 3 Technical Drawings Chapter 4 Shop Practices Chapter 5 Fasteners and Threads Chapter 6 Lubrication Chapter 7 Rigging and Lifting Chapter 8 Shafts and Attachments Chapter 9 Bearings Chapter 10 Belt Drives Chapter 11 Chain Drives Chapter 12 Gear Drives Chapter 13 Couplings and Clutches Chapter 14 Seals Chapter 15 Pumps Chapter 16 Hydraulic Systems Chapter 17 Pneumatic Systems Chapter 18 Prime Movers Chapter 19 Material Handling Systems Chapter 20 Preventive Maintenance Chapter 21 Ventilation and Pollution Control Chapter 22 Installation and Levelling Chapter 23 Alignment Index C") ::r -... Do) -= CD...... MILLWRIGHT MANUAL: CHAPTER 1 Safety WCB regulations............................................................................ 1:1 WCB responsibilities........................................................................ 1: 1 Employers' responsibilitie................................................................ 1: 1 Workers' responsibilities.................................................................. 1:2 Industrial Health and Safety Regulations......................................... 1;2 Job site safety.................................................................................. 1;3 Housekeeping on the job.................................................................. 1:4 Personal safety................................................................................ 1:4 Personal apparel................................................................................ 1:4 Personal protective equipment......................................................... 1:5 Safe operation................................................................................. 1:9 Lockout procedures.......................................................................... 1:9 Tool safety........................................................................................ 1:9 Shop safety equipment..................................................................... 1 :11 Fire safety....................................................................................... 1: 11 The fire triangle................................................................................ 1: 11 Principal causes of fire..................................................................... 1: 12 Classes of fires.................................................................................. 1; 12 First-aid frrefightiug......................................................................... 1: 14 Confined-space............................................................................... 1: 16  Safety Safety in a plant is the concern of government, management, and labour. A healthy safety attitude toward accidents benefits the employee by helping to avoid injury, loss of time, and loss of pay. A millwright is possibly exposed to more hazards than any other worker in a plant and should be familiar with the Workers' Compensation Board (WCB) regulations dealing with personal safety and any special safety rules applying to each job. weB regulations The WCB is a provincial body set up to maintain a safe, healthy, working environment at job sites throughout the Province. It is a powerful legal body and can order unsafe job sites closed until they are made safe. The WCB publishes a handbook: Industrial Health and Safety Regulations. It contains all the rules, regulations, and responsibilities of the WCB, the employer, and the worker. weB responsibilities According to the Workers' Compensation Act, the WCB is responsible for: inspecting places of employment investigating accidents and the causes of industrial diseases assisting and advising employers and workers in developing health and safety programs Employers' responsibilities The WCB dictates that every employer shall keep a copy of the WCB Industrial Health and Safety Regulations readily available at each place of employment for reference by all workers. The handbook begins with a general explanation of terms, the procedure for notification of injury, and first aid requirements. Sections 2 through 8 contain the regulations identifying responsibilities that are common to all places of employment. A few of the employer's responsibilities are noted below. io"iMi!'!.2!.F.:4W;:;,",-cm)t.'i;idHiL"ih"50'1S"_2!_~~"tWif)aR"lM~UJ;.Jij;-I'ii'%Bj,"m;"_2,\P:1i'-8,!;):;'8S3"#9WWb'X0jTh."1SSBB6h"m"{f'!E8_,-~qKG~-{'"%%"'%t,t;;mef&:$D$SBfii'f'i_9_,-;;ef.nR"'''':2;~:i;",i\f!:!lM>;kNVS«iS0X:i1{:«",jo/(i:'JIi:0N1Mj,;;;:p;;r;;\iH'fr4,?\ti7iSIT>t::1:,W'";W,,;,z,,$040Ji-,,-,, MILLWRIGHT-SAFETY 1 -7  Hand protection Accident statistics indicate that over 30% of work injuries happen to fingers, hands, and anns. Many of these accidents could be avoided by the use of appropriate hand protection (see Figure 7). Insulated Coated, abrasion-resistant Leather Natural rubber Rigger's Figure 7 Various types of gloves As a trades person you are ultimately responsible for your own hand protection. Use the correct gloves: Use thermally insulated gloves when handling hot metal. Use rubber or approved plastic-treated gloves when handling acids and cleaning solutions. Use gauntlet-type welder's gloves when welding or flame cutting. Use approved rubber gloves when working with electrical apparatus, but do not use these gloves for any other purpose (you may damage them so they are useless for electrical work). Use leather or vinyl-coated gloves when handling lumber or steel. Foot protection Due to the danger of sharp or falling r 8" objects, you must wear CSA-approved safety footwear. For example, Class I safety boots must be eight inches high and made of leather or some other 1 approved material. They must have steel shanks and steel toes and should carry a green triangle at the ankle to ~::::::::~~~teeIShank indicate they are CSA approved. Figure 8 Safety boot 1- MILLWRIGHT-SAFETY  Safe operation of equipment Operate and shut down machinery properly: Be sure the equipment or machine is free from obstruction and that all personnel are well clear before the machinery is activated. Shut off machinery if you are leaving the immediate area. Allow revolving machinery to stop on its own before leaving it. Do not slow down or stop a machine with your hands. Be sure all machinery is stopped and disconnected before you begin to adjust or clean it. Lockout procedures As a millwright, you may often be in an area where maintenance procedures are being carried out on powered machinery. At these times, detailed lockout procedures are essential to prevent anyone from operating a machine that is being worked on and to prevent the unexpected energizing of a machine. Lockout must involve more than merely disconnecting the power source. Workers have been killed by machinery that was dead electrically but whose hydraulic systems were still pressurized. The machine must be assessed thoroughly, and all energy sources--electrical, pneumatic, hydraulic or gravitational-must be made inoperative, a state often called zero mechanical state. Each millwright should have his or her own lock and key (combination locks are not allowed), and only these locks should be used to lock out energy sources. The machine operator should be infonned of maintenance plans, and the lock should be tagged to identify the person who has locked out the machinery. No one, other than the person who placed the locks and tags, can remove them. Operators and other workers are strictly forbidden to remove either the tag or the lock. Note that these procedures apply not only to stationary industrial equipment but also to mobile equipment, including passenger cars, truck equipment, and heavy construction equipment. Tool safety It is very important to use tools safely. Even a small accident can become a major crisis if no one is around to help. Power tool manufacturers usually build safety features into their equipment. It is a good practice to use all safety equipment supplied. It is illcgal, as well as an unsafe practice, to bypass, disconnect, or remove guards, hoods, shields, ete. !iU"-M2\X¢fe;";;;:;:1€ 1 I ~. Figure 14 Dimensioning a square bolt pattem In a circular pattern, the arc depicting the radius dimension is normally 30" or 45° off the horizontal plane. Preferred Acceptable Figure 15 Dimensioning a bolt circle Arcs, rounds, or fillets are shown in the form of a radius measurement. 3  Views Sectional views Sectional views (or sections) are used to show an aspect of the object which is otherwise too complicated to show with the conventional top, front, and side views. Sectional views may also show differences in materials. A sectional view cuts an object along an imaginary cutting plane. The drawing is sectioned off at the cutting plane to reveal an internal view. Front section removed +--y?~/ Cutting plane line Cutti ng plane -0 Section B - B SIDE VIEW IN FULL SECTION Front section removed +--y;- Cutting plane line Cutting plane Q} +_..JA Section A - A SIDE VIEW IN HALF SECTION Figure 16 Side views in full and half sections  Full-section views use a cutting plane through the whole object giving the impression that the object has been cut in half. Half-sectionals remove only a certain portion of the drawing. If a half- section view gives all the information needed to understand the drawing, then a full section drawing is not given. See Figure 16. Different materials and solid parts A sectional view may cut across more than one type of material. Figure 17 shows some line patterns commonly used to indicate types of materials. These patterns also indicate solid portions of an object. /" /" /" /" /" /" /" /" /" /" /" /" /" /" /" Iron Steel Brass, bronze, copper Figure 17 Patterns indicating different materials Offset sectional views Another type of sectional view is the offset sectional. Offset sectional cutting lines are always of the broken type. Figure 18 shows the necessity for offsetting the sectional view. It can be seen that a normal cutting plane line could not possibly give a proper perspective of the part in question. The lines must be offset to show the outer bolt holes. Figure 18 Sectional and offset sectional cutting planes 3 14 Other types of sectional views Other types of sectionals include aligned sectional (Figure 19), revolved sectional (Figure 20), removed sectional (Figure 21), and broken-out sectional (Figure 22)... 1/ Cutting plane line i / / /. /// j..._.. Aligned / Angled elements must be aligned sectional view Figure 19 Aligned sectional view ~IOE Figure 20 Revolved sectional view 3 15  A B ~ ~ I I I " ' I I I : I I Section A·A Section B·B A B Figure 21 Removed sectional view Figure 22 Broken-out sectional view Auxiliary views Auxiliary views are used to detail sloping (or inclining) surfaces which cannot be depicted in normal orthographic views. Auxiliary drawing clearly shows the shape of thc object and gives its true dimensions. 3-  Auxiliary views are created by projecting the lines of the object where the sloping surface appears as an edge. See Figure 23. Surface A Surface B Surface B a. Regular views do not show true features of surfaces A and B Surface B Partial top view Surface A Partial auxiliary view Partial side view D b. Auxiliary view added to show true features of surfaces A and B Figure 23 The need for auxiliary views Occasionally an object cannot be completely described in one auxiliary view, so an additional auxiliary view may be needed. iG_~·~{gj(©"'«IiXi:vBiiii,:0iMhLo;2i;;j1;"Y.t;'-ill?ii"~;'!ii!ii!m,\'4'!i!iitiA'%J-'"_9'S"!ii!'i'ii'!&'Si-"'-;;_M;.'i'\,!K"'EHXWii'ib'?i*fi+ co '" 0 '" z i '" s·'iil" 0 o ~ i 0 Very rough surface. ~ Eq uivalent to sand casting. ~ ~ co ~ 0 ",z s· ~ q Rough surface. ~ ~ 0 0 '" ~ ~ z -" Rarely used. (/) ~ Ib '" ~ ''"" I- L- ~z :::!. ~ I Coarse finish. Equivalent to '" }@'*:8S;8P':8l:;8-'O:;8';';:!W0_::;W,,';l';'%:Y'iX!i:'iX!iE8idb~S"Wjiji~;Bjhim11;$)f'lo~'%'m%B%IW~;&,P¥W_R:8l:;';-J~'M;hOO4"&"6?$~~:G MILLWRIGHT-TECHNICAL DRAWINGS 3 - 29  Figure 36 A schematic diagram of a hydraulic system Figure 37 A schematic diagram of a pneumatic system  Start Stop.....L... M M M OL Figure 38 A schematic diagram 01 an electric circuit Piping drawings Piping drawings are a little different from schematics. The typical example shown in Figure 39 displays all the important pieces in symbolic form like a schematic of a hydraulic system. However, this diagram not only shows functions, connections, and flow, it may also locate the pipe spatially. Single-line and double-line pipe drawings The single line pipe drawings shown in Figure 39 display the pipe in isometric and orthographic projections. Notice how the spacing and location of pipe gain importance. Figure 40a shows a double-line drawing. It also shows the difference between the older single-line drawings (Figure 40c) and the current single- line technique (Figure 40b).  Pipe line a -Tee Elbow 40 a. Isometric -- ~ \ I ,~ _ ' - ' - Adjoining apparatus (tank) _Naive / A 80 _ L __ ~ _1-1_-, 1___ ___ _ I --.I------l if c 35 i Tee A Pipe line L -_ _ _ _ _ _:- - - - - , -_-+,_--, -------.,~ '~ Adjoining apparatus (tank) b. Orthographic Valve I I f 'a 40 A ,- - - - - - - '", Elbow A 1_ _ _ _ _ _ - -,.".. , ,~~~ Figure 39 Piping drawing 3  +- - -- --------- Cross ~ Plug - ~ " " Lateral a. ~ [~======~ J_ Tee ~ Flanged Check 45° elbow joint valve I' t -,] '-------.!.--1 , I I' Cross b. I Elbow Globe valve I Plug Gate valve / i n lines for fittings.~ Lateral Thick lines for Cap L Tee pipe and flanges Flanged Check 45° elbow L joint valve Elbow (used only to indicate direction of pipe) Elbow ~ I Cross - '"1 Lateral l ,I r- Cap Globe Gate valve Plug valve ~ c. Tee Flanged Check 45° elbow joint valve 1- Elbow Figure 40 Single-line and double-line piping drawings 3 33  Symbols and abbreviations Symbols are the shorthand signs used on drawings. These symbols tell the tradesperson what to do, and where to go or not to go for information. These symbols are for the most part international but some countries have different symbols. Accredited organizations like the International Standards Organization (ISO), Canadian Standards Association (CSA), and American National Standards Institute (ANSI) publish tables of symbols for welding, piping, surface texture, and electrical elements. For a listing of symbols, refer to the appropriate published standards. For a selection of hydraulic and pneumatic symbols please refer to Chapters 16: Hydraulic Systems and Chapter 17: Pneumatic Systems. !t.'Wih','ia.O'f.'!Nh\W/'i!f%.!r!"tr C; ( IZCIv. This thread has flat crests and roots and a 29° included angle. The crest and the root have slightly different widths, wI and w2 in Figure 5. Square threads are difficult to produce and tend to break off at the corners. The 29° thread form prevents binding while increasing the applied foree. Figure 5 Acme 29° screw threads (,\I u.-l.,I:>Cl) ff>Jc, IE " National Pipe Taper (NPT) Thread This tapered thread seals the joint, preventing leakage. In standard pipe threads, the flanks come in contact frrst. There can be spiral clearance around the threads. In dry-seal pipe threads, the roots and crests engage frrst, eliminating spiral clearance. These threads are called American dry-seal threads (see Figure 6). Spiral clearance NPT Dry seat Figure 6 Pipe threads Figure 7 shows that if the pipe bottoms out too soon (touches the end of the internal threads) the threads may still fit loosely without a good seal. /.kofl'('. ?l::VJf Sc-rrL 314" laper per foot Figure 7 Tapered pipe thread ISO metric series The International Organization for Standardization (ISO) sets this series as the standard metric thread shape, pitch and sizes used throughout the world. The ISO series has thread sizes ranging from 1.6 to 300 nun. It also has a 60° included angle and flat crests and root~. The ISO thread has a crest equal to 0.125 times the pitch. The main differences are: The depth of thread is less. The root is 0.250 )( pitch. The larger root diameter allows an increase in the tensile strength of the fastener. Table 1 shows common combinations of pitch and diameter. Table 1: Some ISO metric pitches and diameters Nominal diam. Thread pitch Nominal diam. Thread pitch (mm) (mm) (mm) (mm) 6.0 1.00 64 6.0 8.0 1.25 72 6.0 10.0 1.50 80 6.0 12.0 1.75 90 6.0 14.0 2.00 100 6.0 16.0 2.00 Figure 8 shows ISO metric threads. Figure 8 ISO metrie threads In print, a metric fastener is described as in the following example: M8 )( 1.25 )( 50 nun where: M = the symbol for metric 8 = the nominal (major) diameter in nun 1.25 = the pitch in mm 50 rum = length offastener Variations in thread size and pitch As the diameter of the bolt, screw or nut decreases, the size and pitch of the thread become less. For example, UNC threads on a 1/4" diameter bolt are smaHer and closer together than UNC threads on a 1/2" bolt.  Table 2 shows standard imperial or inch sizes of bolts and nuts. The chart lists threads per inch for various diameters of both UNC and UNF fasteners. Table 2: Sizes for common nuts and bolts Major Threads Thread Major Threads Thraad..........- ciillrneter per inch series diameter per inch series 1/4ft 20 UNC 11/a" 7 UNC 2B UNF 12 UNF 5116" lB UNC 11/4" 7 UNC 24 UNF 12 UNF 3/a u 15 UNC l1f2' 6 UNC 24 UNF 12 UNF 7/16" 14 UNC 13/4" 5 UNC 20 UNF 12 UNF 1/2" 13 UNC 2" 4 /2 ' UNC 20 UNF 12 UNF 9h6" 12 UNC 2114" 4 /2 ' UNC 1B UNF 21f2' 4 UNC 5/a" 11 UNC 23/4 " 4 UNC 1B UNF 3" 4 UNC 3/4 " 10 UNC 31f4" 4 UNC 16 UNF 3'/2" 4 UNC 7/e" 9 UNC 33/4" 4 UNC 14 UNF 4" 4 UNC 1" 8 UNC 12 UNF 14 UNF Not all pipe threads have the same pitch. Larger pipes have threads of a larger pitch as is shown in Table 3. Table 3: Sizes for NPT threads /\iominal Ilille size tilL OD to nearest '116" 1/ar! 27 7/1611 114" 1B 911611 3/a l1 18 11116 11 1/2." 13 14 11611 3/4 " 14 1'116" 1" 11'/2 15116 11 1'/4" 11'/2 111/16" 11/2. 11 11'/2 11511611 2' 11'/2 23/8 11 2'/2" B 27/8 11 Types of fasteners Threaded fasteners are classified as either studs, screws or bolts. The distinction is that a screw is loaded by a head, and a bolt is loaded or tightened by a nut, but some fasteners can be used either way. Using a cap screw as both a bolt and a cap screw will reduce the parts inventory. Threaded fasteners (r:j}......... Nut Bolts and nuts, cap screws and studs are threaded fasteners with various functions. A bolt is held and tightened with a threaded nut. Bolts (with nut.) are used to join two or more components as shown in Figure 9. Figure 9 Nut and bolt Cap screw A cap screw is similar to a bolt Threaded ~ except that it is threaded into a hole". tapped (threaded) hole rather than into a nul Figure 10 Cap screw A stud is a rod that is threaded on both ends. Some have coarse threads on both ends. Others, for soft metals such as cast iron, aluminum or 1--="",- Stud brass, have coarse threads on one end sO that it can be threaded into the soft metal without stripping it. The other end has fine threads to achieve a good clamping force with the nut. See Figure 11. Figure 11 Stud and nut Classification of fasteners Bolts, nuts and cap screws are classified in three ways-by their: tensile strength design (or shape) size and thread pitch Tensile strength Threaded fasteners can be made from a number of different materials such as steel, stainless steel, brass, aluminum and even plastic. The most common material used is steel. Different grades of steel are used for their different tensile strengths. Tensile strength is the ability of a material to resist forces that tend to pull it apart. To identify the tensile strength of a fastener, grade markings are stamped on their heads during manufacture. Table 4 shows the general specification of fasteners. The head markings for both imperial and metric fasteners are shown so you can compare them. Table 4: ASTM, SAE and ISO specifications for steel bolts and screws Head marking Specification Tensile strength minMPa min psi IMPERIAL 0 ASTM-A307 SAE-Grade 2 450 65000 0 SAE-Grade 3 760 110000 0 ASTM-A325 SAE-Grade 5 830 120000 © ASTM-A345 SAE-Grade 8 1040 150000 ® High strength L9™ 1170 180000 © Socket head Cap screws 1240 170000 METRIC 0 ISO R898 Class 8.8 830 120000 0 ISO R898 Class 10.9 1040 150000 © ISO 4762 Class 8.8 830 120000 © ISO 4762 Class 12.9 1220 177 000  imperial size fasteners often use a number of slash marks on the head to identify the grade. To determine the grade of a fastener, you can usually count the number of slash marks and add two. For example, Figure 12 shows a grade 5 bolt. Note that the identification rule Is not consistent. For example, an SAE grade 3 bolt or screw 3 slash marks... 2 ; grade 5 head has two slashes rather than one. Figure 12 Identifying imperial size bolt grade Metric size bolts use a numbering system that identifies the class of the bolt. Tensile strength increases as the number stamped on the bolt head increases. Design Bolt design A number of different head desigus are used in the manufacture of bolts. The three main types are shown in Figure 13. Carriage bolt Hex-headed boll Square-headed bolt Flgure13 Bolt head designs Carriage bolts are used in applications where a smooth, round head is desired. The square shoulder is designed to prevent the bolt from turning when the nut is tightened. Because the head of a carriage bolt cannot be turned once the bolt is installed, carriage bolts are often used to provide added security. Hexagon-head bolts are by far the most common. Hexagon heads provide a new gripping surface for a straight wrench each time the bolt is turned 60°. They are much more widely used, because they can be tightened more easily in cramped quarters. Square-headed bolts are found on some industrial equipment They must be turned 90° before the wrench can be relocated on the head. Cap screw design The most common head designs for cap screws are hexagonal and socket head. The nominal sizes of cap screws start at 1/4". For installations where the cap screw head is to be set below the surface, socket-head cap screws are available (Figure 14). Figure 14 Socket-head cap screw Nut design Nuts are available in a wide range of designs, and again, each design is intended for a particular application. The following are some of the more common designs in use today. Hexagonal (hex) nuts (Figure 15) are general purpose nuts used in almost any location where a strong nut is required and there is limited access. Figure 15 Hex nut Square nuts (Figure 16) are most often used in locations where access is unrestricted. Square nuts offer a larger flat surface for the wrench jaws to grip; therefore, they are able to withstand greater torque (twisting force) than hexagon nuts. Figure 16 Square nut Slotted hex nuts (Figure 17) are similar to a regular hex nut except that slots are cut into the top to receive a cotter pin. The cotter pin is inserted through the slots of the nut and a hole in the bolt. Figure 17 Slotted hex nut Castellated nuts (Figure 18) are locking nuts that also use a cotter pin to prevent the nut from turning. Figure 18 Castellated nut Stover™ nuts (Figure 19) are self- locking nuts that have their top inner surfaces bent inward. When the top part of the nut is tightened onto a bolt, this oval part is forced back to round, causing resistance to turning. Figure 19 Stover™ nut  Nylon lock nuts are another type of self-locking nut as shown in Figure 20. When the nylon lock nut is tightened on a bolt, the nylon is forced to stretch, causing resistance to turning. Figure 20 Nylon lock nut Jam nuts (Figure 21) are thinner than regular hex nuts and are used as a locking device. When used to lock a regular hex nut, the jam nut should be between the hex nut and the joint surface so that the hex Figure 21 Jam nut nut takes the full bolt load. PallUltsTM, illustrated in Figure 22 are an even thinner version of the jam nut. Figure 22 Painut™ Size and thread pitclI The size of a nut or of any internal thread is identified by the major thread diameter and thread pitch of the bolt that would fit the nut. The thread pitch of any bolt or nut can be determined by using a thread-pitch gauge as shown in Figure 23. Figure 23 Thread-pitch gauge (imperial) Machine screws Machine screws are a special group of screws 3/8" or less in diameter; they have their own sizing system. The term "screw" is correct as they are generally used without nuts. Nuts are available, however, for all sizes of machine screws. Unlike bolts, when nuts are used with a machine screw, the name "machine screw" still applies. i Charts show machine screws designated by numbers from 0 to 12. Above this, they are designated by fractions. These numbers indicate the diameter of a machine screw, for example, a #6 has a diameter of 0.138 inch. ' To find the diameter of a machine screw in inches: multiply the screw number by 0.013 add 0.060 Example 1 Find the major diameter of a #6 machine screw. 6 x 0.013 = 0.D78 0.078 + 0.060 = 0.138 Major diameter = 0.138" Example 2 shows how the letters aud numbers are used to specify a machine screw by its threads per inch, length, and head-type: Example 2 What is a "#8 - 32 x 112 PAN HEAD" screw? The letters aud numbers indicate a machine screw with a #8 diameter of 0.164" (calculated). It has a pauhead, 32 threads per inch, aud a length of 112" from the underside of the head to the end. There are several variations of machine screws: The self-threading or self- tapping machine screw is commonly used in industry. The self-tapping screw is harder thau a regular machine screw and has a specially formed tip that resembles a threading tap. The thread has the same appearauce as the thread of a machine screw See Figure 24. Figure 24 Self-tapping machine screw tips The self-tapping machine screw is installed into a drilled hole slightly smaller thau the major diameter of the screw. When you engage the self- tapping machine screw into a drilled hole, the machine screw cuts threads into the sides of the hole. Sheet metal screws are auother variation of the self-tapping screw. These self-drilling, self- tapping screws are generally used on thin material such as sheet metal (Figure 25). They are also available in several head styles. Figure 25 Sheet metal screws  Washers and locking devices Washers Flat or plain washers are steel disks with a hole through their centres (Figure 26). They are used under bolt heads and under nuts to increase the bearing su!face of the fastener. Plain washers also protect surfaces from being damaged by bolt heads or nuts. Figure 26 Flat steel washer Plain washers are identified by the closest size of bolt that fits the hole in the washer. The inside diameter of a washer is about 1/32" larger than the bolt size. For general use, washers are made from mild steel. Split-ring lock washers are used to keep nuts and bolts from becoming loose as a result of machine vibration. Sizes of lock washers correspond to the bolt that fits them. See Figure 27. Hi-collar lock washers are like split washers but thicker and stronger. Split ring Hi-collar Loose Tight Figure 27 Split-ring lock washer and hi-collar lock washer Tooth-lock washers are used when extra holding power is required. The teeth are angled to allow the fastener to be tightened. Each tooth grips the su!faces to prevent the fastener from loosening (Figure 28), They are also available in a cone shape to fit countersunk heads (Figure 29). Figure 28 How a tooth·lock washer grips A Do not use lockwashers on flat washers  External Internal External/internal Cone washer Figure 29 Tooth-lock washers Pins Pins are used to lock two or more parts together. Sometimes pins are used to accurately position one part to another. Cotter pins (Figure 30) are inserted through the slots of the nut and a hole in the bolt. The prongs are then bent j-",.,", Figure 30 Cotter pin back to keep the pin in place. Figure 31 shows the correct way to bend the prongs so that the cotter pin secures the nut without leaving jagged ends protruding. If the prongs are too long. cut them back with side cutters. Slotted nut Figure 31 Bending colter pin prongs Headed pins (or clevis pins) are most often used to attach a part to a U-shaped yoke known as a clevis. Figure 32 shows a clevis pin used to attach a part to a turnbuckle. Clevis pin Figure 32 Use of a clevis pin in a turnbuckle Taper pins are used to fasten machinery parts that must fit precisely (Figure 33). The taperratio is 1:48 (1/4" per foot) The pin is driven into a matching tapered hole. Figure 33 Taper pin  Dowel pins are used to aid in aligning two machinery parts. They are straight round stock with a slight chamfer at each end (Figure 34). The chamfer serves to get the pin Chamfer started. Some dowel pins are hardened j and ground for strength and precision. Some have an exposed end threaded or (0 tapped for easy removal. Figure 34 Dowel pin An example of dowel pins use is shown in Figure 35. The dowels are fitted tightly into matching holes on both machine parts. This lines the parts up for accurate assembly. Figure 35 Using a dowel pin to line up parts Shear pins are used to connect a gear or other part to a shaft. They are designed to tolerate oaly the normal load imposed on machinery parts. Under greater than normal loads they shear, stopping the part being driven. This prevents more serious damage to the rest of the machine. They are made of a softer material or have a groo ve where they are designed to shear. Figure 36 Shear pin Spring pins and roll (coiled) pins are hollow cylinders of spring steel. The spring pin is split lengthwise (Figure 37a) and bevelled at each end. The roll pin curl~ around itself as shown in Figure 37b. These pins are made slightly oversize so that when driven or pressed into place, they compress. This causes outward pressure which holds the parts in place. I+--(Cm _----+(() (a) (b) Figure 37 Spring pin and roll pin  Grooved pins are solid pins with a slot along their length. On some pins the slot or groove runs the full length of the pin, but is only partly through the pin. On others the slot may be shorter than full length but may go right through the pin. Grooved pins have tremendous holding power because they expand when driven into place. Grooved pins are designated by type, nominal diameter and length. and material. Their types are identified by letters as shown in Figure 38. Q D F-~- _3 Type A TypeC TypeE f 3 TypeB Type D Type F Figure 38 Types of grooved pins Convenience pins are quick and easy to install and remove. They are designed as retaining pins rather than as pins to withstand great loads. Two common types of convenience pins are spring-locking pins and quick-lock pins. - Spring-locking pins are often called hairpin cotters (Figure 39). They are used instead of a cotter pin to hold other pins in place when they must be installed and removed frequently. Figure 39 Spring locking pin The straight leg of the pin is inserted through the hole in the end of the clevis pin. The bent leg is forced up and over the side of the clevis pin. - Quick-lock pins are used to secure removable attachments to a machine (Figure 40). They have a split spring-steel ring mounted at the head end Figure 40 A quick-lock pin Once the pin is installed, the ring is rotated down over the end of the shaft to prevent the pin from coming off the shaft. Sometimes a quick- lock pin has a short length of chain to attach the ring to the machine. This prevents the pin from being lost. Cutting threads Taps for internal threads Taper QQ~:~~§§!EEE3~ The tool used to cut internal threads is a tap. The process is called tapping threads. The three Plug QQ~:§§§!~~ types of taps shown in Figure 41 are for different stages of a cut. Bottoming Qb)~:§~~~ Figure 41 Tap types Taper taps have a taper, or gradual narrowing of the shaft, that extends for approximately six thread pitches. The threads on a taper tap are shallow at the narrow end ofthe tap, and gradually increase in size to full thread depth at the top. A taper tap is used to start the thread-cutting process because this long taper permits gradual removal of the metal as the tap is turned into a pre-drilled hole. If the hole to be threaded is drilled completely through the material, the entire screw thread may be cut using a taper tap. Plug taps have a taper only half the length of the taper on a taper tap (three thread pitches). They are used to cut threads in blind holes (holes that are not completely through the material). The plug tap is not designed, however, to cut full threads right to the bottom of a hole. For this reason, it has to be used in conjunction with a bottoming tap. The bottoming tap has only a very short taper Gust one thread pitch). When the plug tap has been inserted as far as it can go and then removed, the bottoming tap is used to cut the threads down to the required depth. Tap wrenches A tap wrench is used to hold the tap securely so that forces are applied evenly to the tap. It also makes it easier to keep the tap in line with the hole. Tilting the tap during a thread-cutting operation usually results in the tap breaking. Figure 42 shows a T-type tap wrench. Once the tap is inserted into the wrench, the chuck is turned to Figure 42 T-type tap wrench tighten its jaws onto the tap. Larger taps require more force to turn them during thread-cutting. Therefore, G a longer tap wrench (see Figure 43) is required. You can adjust the jaws of the wrench to fit the square end of the tap by turning one end of the handle. Figure 43 Tap wrench for large taps  Tapping threads The procedures for tappiug threads are quite straightforward. The main thiug is to work carefully aud avoid forciug the tap uuevenly. Taps are very brittle aud cau break. Determine and drill the size of hole required 1. Detenniue the thread size and pitch. 2a. Detenniue the diameter of the hole to be drilled from a tap drill size (TDS) chart. The hole diameter may also be listed On the side of the tap. Making the hole smaller than listed on the chart will cause too much strain on the tap. If the hole is made larger thau listed, the threads will not be deep enough aud will tend to strip easily. 2b. If no tap drill chart is available, determine the size of hole by using the nomiual diameter: TDS = nomiual diameter - pitch Example 1: Select the drill to tap for a 1"- 8 UNC screw. An 8 UNC screw has 1/8" pitch IDS = nominal diameter - pitch = I" - l/S" = 7/S" Example 2: Select the drill to tap for an MIO x 1.5 screw. An MIO screw has 1.5 mm pitch IDS = nominal diameter - pitch =10mm-1.5mm =8.5mm A Make sure the workpiece is clamped securely for all stages of drilling and tapping. 3. Drill the holes for taps accurately. When you cannot use a drill press, use a portable drill as accurately as possible. Check the taps 1. Make sure the tap is the correct size aud the hole is the correct size for the tap. 2. Always wipe taps cleau before (aud after) usiug them. 3. Check the cuttiug edges of the tap to be sure they are sharp. Dull cutting edges require more force to turn the tap, which may break it. Tap the threads 1. Correct alignment is essential when the tap first enters the hole. Once the tap is started correctly, it will tend to remain aligned. If the tap is out of alignment, remove it and start over. Apply equal amonnts of pressure on each end of the tap wrench. Don't try to force the tap into alignment, or it may break. 2. Carefully and gently start the appropriate tap in the hole. You will find the tap will soon appear to jam. Turn back slightly more than a quarter tum, tum forward to where you were and continue forward a half tum. The tum backwards breaks off the spiral chips formed by the cutting process. Once the chips have broken free, they can fall away. 3. Lubricate frequently during tapping nnless the material being tapped is cast iron. The lubrication reduces friction and prevents excess heating of the tool and material. It also prevents excess tool wear and helps wash away chips formed by the cutting. Use a lubricant recommended for thread cutting. 4. When the tapping is complete, remove the tap and clean the hole. Broken tap removal Always wear eye protection whenever you strike a broken tap. The tap material is very hard and brittle and flying chips could cause eye injury. Tap extractor method The tap extractor (see Figure 44) is a rather delicate tool, but it can work well and save a great deal of time if used correctly. To use the extractor, do the following: 1. Before using the tap extractor, try to break loose any chips caught between the tap and the sides of the hole. Do this by jarring, probing, or picking the area. 2. Place the "fingers" of the tool in the flutes of the broken tap as far down as possible. 3. Pull the collar down to the top of the broken tap. 4. Use a tap wreneh to tum the tap extractor. Turn them back and forth to work the tap out of the hole. Figure 44 Tap extractor Punch and hammer method A small punch and hammer can also be used very carefully to loosen the broken tap as shown in Figure 45. Always use plenty of anti-seize liquid when attempting to remove a broken tap. Figure 45 Loosening a broken tap Heating and cooling method This method of tap removal must be done carefully to avoid damaging the workpiece. I. Heat the broken tap with a torch. 2. Chill it immediately. Methods of chilling the heated tap varies depending on the situation. Sometimes cold water is used. Other methods include using CO2 in gas or dry ice form. 3. Immediately after cooling the heated tap, try to turn the tap out of the hole. 4. It may take two or three heatings and chillings before the tap will move. Dies for external threads The tool used to cut external threads is a die. Dies such as those shown in Figure 46 have four cutting edges that cut the threads as the die is turned. The two dies shown can be adjusted slightly for accurate piteh diameters. Figure 46 Adjustable dies As the din starts to cut threads on a rod. the cut is quite shallow. It is made deeper as the die is turned until it reaches the full depth of the thread. The die on the left is made to cut threads shallower by tightening the set screw of the die stock into the split in the die. The die on the right has a built-in adjusting screw which forees the split to open, causing it to cut less. Die stocks Dies are designed to fit into die stocks such as those illustrated in Figure 47. Set screw Set screws I /\ Figure 47 Die stocks The die has a small dimple drilled into its side which coincides with a set screw in the die stock. When the set screw is tightened into the dimple. the die is secured to the stock. Figure 48 shows a die stock used while cutting external threads. Figure 48 Using a die stock Cutting external threads Many of the precautions and procedures used for tapping internal threads also apply to the cutting of external threads. Prepare the work 1. If you are cutting external threads to match a threaded part. you must select a rod of appropriate diameter. A rod too small in diameter will end up with threads that are too shallow; rods too large in diameter will either not allow the die to engage or make cutting very difficult. 2. Make sure you select the correct size die. Remember, size includes both the thread diameter and the thread pitch. 3. Secure the die to the die stock by engaging the set screw(s) in the dimpJe(s). 4. Secure the rod to be threaded in a vise so that the workpiece will not move during thread cutting.  5. Start the cut with the die opened as wide as possible. You can al ways cut the threads deeper if needed, but if the threads are cut too deep at first, the workpiece is ruined. 6. Apply thread-cutting fluid often and freely to the area where you are cutting. 7. Make sure all four cutting surfaces of the die are in contact with the rod end at the start of the cut. Apply even pressure to both handles at all times to prevent forcing the die out of alignment with the rod. Check often to make sure the die and the rod are correctly aligned throughout the cutting process. Cut the threads 1. Turn the die stock slowly to start the thread-cutting process. Turn the die backwards just over a quarter turn after every half torn forward. The backward torning will break and clear the chips from the cutting areas. 2. As soon as enough threads are cut so that you can test their fit, remove the die and test the threads on a nut or another internal thread. 3. If necessary, adjust the amount of material being removed by adjusting the split opening ofthe die. When the die is correctly adjusted, continue cutting threads. 4. Clean the die before storing it. ) If a situation arises when you must cut external threads the full length of a bolt: 1. Cut the threads as far down the length as possible in the usual manner. 2. Remove the die from the workpiece. 3. Turn the die over so that the tapered end points away from the bolt, and thread the die back onto the bolt. 4. When the die reaches the end of the threaded portion, continue cutting threads until they have been cut to the end of the bolt. Installation, removal and repair of threaded fasteners Thread repair Slight damage There are occasions when screw threads, internal or external, become damaged and will not mate with other threaded fasteners. In such cases the threads can be quickly made usable by repairing them with tools such as taps, dies, thread chasers, thread fIles and die nuts. Severe damage When internal threads are worn, stripped, or badly damaged, they are usually repaired by one of the four methods outlined below. If the cap screw can be larger: Drill and tap the hole in the machinery part to suit the next size of suitable fastener. Use a larger diameter cap screw. The part held by the cap screw will have to be drilled larger to allow the oversized cap screw to fit. If the cap screw size must remain the same: If the material is weldable, plug weld the hole, drill and tap. Drill the hole deeper if you can and use a longer fastener. Repair the damaged internal threads by using a thread-restoring insert. Thread-restoring inserts (HeliCoils™) HeliCoils™ may be used to provide threads that are stronger (and more wear- resistant) than the material they are used in. HeliCoils™ are formed from diamond- shaped, stainless-steel or phosphor-bronze wire. They have a driving tang and a notch to help in their installation. See Figure 49. Before installation, HeliCoils™ are slightly larger in diameter than the threaded hole into which they are to be inserted (see Figure 50). To use a HeliCoil™: Figure 49 HeliColITM 1. Drill out the damaged threads and re- tap the hole with a special tap. 2. Insert a HeliCoil™ with the special tool. Adjust it until its top end is a quarter- to a half-turn below the top surface of the tapped hole. 3. Once the HeliCoil™ is correctly inserted in a threaded hole, it restores the hole to its original size. 4. Mter insertion, you can easily break the driving tang off with a punch. If the insert reaches the bottom of a blind hole, it may not be necessary to break the driving tang off. Figure 50 HeliCoil™ insertion Broken stud removal Studs or cap screws often become seized in a threaded hole. Then, when you try to remove them, they may twist off rather than come out. When a stud is broken off in a threaded hole, the procedure used to remove it depends on: o how tight the threads fit o whether the fastener broke above, below, or flush to the surface of the threaded hole Tight or rusted studs o If rust seems to be the cause of the seized threads, apply lots of penetrating fluid to the threads. After allowing time for the liquid to penetrate to all the threads, try to turn the stud out. o If rust is not the problem (for example, corroded aluminum), do one of the following: Either 1. Heat the surrounding material, let it cool slowly. 2. Then try to turn the stud out. Or 1. Heat the stud directly and cool it down quickly. 2. Then try to turn the stud out. Broken studs Studs that are broken off well above the surface of the threaded hole may be turned with locking pliers. If the portion above the hole is too short for a good grip with pliers, do one ofthe following (see Figure 51): o slip a nut over the broken stud and plug weld it o hacksaw a notch to accept a screwdriver o file the sides to accept a wrench. Then turn the stud out, using a screwdriver or a wrench. Weld File two flats t t t Figure 51 Stud removal Studs that have broken flush or below the hole require that you: 1. Grind or file them flat if possible. 2. Use a centre punch to make a small dimple in the centre of the stud. Drill a 3 mm (W') diameter pilot hole into the stud. 3. Select a stud extractor that has a diameter approximately half that of the broken stud. Three types of stud extractors are shown in Figure 52. Figure 52 Stud extractors 4. Drill a hole into the centre of the stud to accept the selected stud extractor. Be careful not to drill past the bottom of the stud into the material. 5. Tap the stud extractor into the drilled stud until it has gained a good grip on the inside surface of the broken stud. 6. Use a wrench to turn the stud extractor counterclockwise to remove the stud. You may have to apply penetrating oil. or anti-seize fluid, or you may have to heat and cool it before the stud breaks its grip. Failures during installation Fasteners may fail in three ways: The shank may break. The external thread may strip. The internal thread may strip. This can be caused by incorrect torque. machine vibration, and many other factors in the machine's operating environment. A voiding failure Shank breakage can be avoided by following manufacturer's torque values for assembly. Thread stripping can be avoided by: using deeper nuts SO that more threads are engaged and take the load ensuring that the fastener is strong enough For example, if a bolted assembly is torqued to 136 N.m (100 ft.lbf) to suit specifications, several factors are involved during tbe tightening procedure: torque or turning force, set by the wrench tension or elongation of tbe bolt compression of the material between the bolt head and nut dilation or the tendency of the wedge shape of the thread to enlarge the diameter of the nu t Mter torque force is taken off the assembly, the major force remaining is the tension set up by the fastener. Tensile forces Tensile force on tbe material can be classed as: elastic limit-the amount a fastener can be stretched and still return to its originallengtb after tensile forces are removed. Proof-load figures for fasteners are frequently given; they are slightly less than tbe yield load of tbe fastener, but within the elastic limit. yield point-where the fastener begins to take a permanent set ultimate tensile strength (uts) -tbe failure or breaking point These forces are expressed in pounds per square inch (psi), tbe units of stress. They represent tbe forces tbat will break a length of material witb a cross section of one square inch. Preload in fasteners Preloading means tightening a nut and bolt assembly to a predetermined torque value. This prepares the nut and bolt to accept an opposing load. Torque wrenches are tbe most frequently used tool to induce this preload into nut-and-bolt assemblies. For example, torquing the bearings and tbe bearing end caps, preloads tbe bearing assembly to counteract the tbrust forces in the loaded shaft. Uniform preloading It is often important to have uniform preloading in a system. Preload is applied by several methods: Preload indicating washers-These washers are designed to crush at their highest points at a predetermined torque value. For example, in Figure 53, the washer has protrusions when flattened as the bolt is tightened. A feeler gauge is used to measure the remaining gap between the nut and the assembly surface. With a paired bolt and load-indicator washer, tbe amount of gap is proportional to bolt preload. A set of manufacturer's tables is needed for each washer, and you must assemble tbe bolts and washers carefully.  Type A-325 TypeA-490 (a) (b) Washer Feeler gauge (el Figure 53 Load-indicator washers Preload indicating bolts-provide visual or physical evidence that the desired preload value has been reached. They have various designs such as the wavy flange bolt (see Figure 54) and the spinning cap bolt. - The wavy flauge type has a wavy flange under the bolt head which flattens when desired preload is reached. The spinning cap type has a spinning cap on the head of the bolt. As preload is reached, the bolt stretches and the cap locks in place. Figure 54 Wavy-flange bolt before and after tightening Torque nuts and torque boUs-are specialized fastening systems. They are used in areas where high bolting tension is required, such as in high- pressure flanges, turbines, compressors, pumps and anchor bolts. Either torque nuts or torque bolts are used, not both. A hardened washer must be used under the torque nut or bolt see Figure 55. This system achieves very high clamping loads (preload) with low torque.  Example: A 11/2 - 12 cap screw tightened by a nut using conventional methods requires 2194 ft.lbf to achieve 87 750 lbf preload. A torque nut with 8 jacking screws requires 44 ft.lbf per jackscrew to achieve the same preload. When working with these nuts and bolts, refer to the manufacturer's specifications for torquing procedures and torquing tables. Torque nul Jacking screws Torque bolt Hardened washers Figure 55 Using torque nuts and bolts Measured elongation offasteners-Uniform preloading gives uniform elongation of fasteners. A micrometer reading is taken for the length of each fastener. On assembly, each fastener is stretched to a specified uniform length. Tum of the nut-In this method the fastener assembly is snugged up to a "tight-by-hand" position. The nut is then marked with chalk or pencil and turned 1 to 1 112 more turns. This is usually done with an impact wrench or a slugging wrench (see Figure 56). A Always use safety glasses when using a slugging wrench.. Striking face box wrenches 45° offset 12 point opening -------"'~-\ C!o/.----~, ~--~ Figure 56 Slugging wrench  Torque wrenches A torque wrench is used to ensure that the correct amount of preload is put into each fastener. Manufacturer's specifications must be followed at all times. Any deviation from these specifications could fracture or deform a machine component, resulting in premature failure. Use torque wrenches only for tightening fasteners. A Never use a torque wrench to loosen afastener. Torque-limiting wrench The torque-limiting wrench automatically releases when the preset torque limit is reached. Direction selector Micrometer barrel ~~!U~~==~~!*~n:"" Ratchet head Handle of wrench showing torque setting Figure 57 Torque-limiting wrench Dial-indicating torque wrench Smooth, even o pull o In the dial-indicating torque wrench (see Figure 58), torque is shown on a dial face on the handle. Figure 58 Dial-indicating torque wrench Deflecting-beam torque wrench In the deflecting-beam torque wrench, the amount of torque being applied to the fastener is shown on a scale situated on the wrench main frame. The scale may be graduated in imperial and/or metric.  Socket drive head Deflecting beam ---~~..l.~6e.:/'"--- Scale Figure 59 Deflecting-beam torque wrench Torque multiplier A torque multiplier uses the ratio principle. See Figure 60. 1/2" drive _ 111 drive ------+- Figure 60 Torque multiplier Hydraulic torque wrenches Hydraulic torque wrenches are used where high torque is required to tighten fasteners. Hydraulic pressure applied to a piston forces a lever to rotate the drive. A reaction arm against a fIxed surface of the machine keeps the tool from rotating. Pressure is supplied to the wrench from a portable pump and tank. To get the pressure gauge reading for the required torque, refer to the manufacturer's conversion tables. Socket drive Reaction arm Figure 61 Hydraulic torque wrench Using adapters Sometimes it is not possible to use a socket on the torque wrench. This is overcome by using a crow's foot adapter as shown in Figure 62. An adjustment to the scale is needed to account for the extra length of the wrench. Figure 62 Crow's foot adapters Torque values The torque values shown in service manuals are designed to: give correct preload on fasteners prevent shear across the thread when assembling ensure a uniform loading on all the fasteners when assembling prevent distortion, failure or cracking of metals, e.g., a cast bushing used with steel cap screws provide standards Values given in the tables in service manuals usually apply to a new threaded assembly (Class 2A or 2B) with very light lubrication. Correct torque Correct torque values depend on: accuracy of the torque wrench thread finish type of surface finish on the fixed and turning metals class of fit condition of the fasteners positioning of the holes correct amount of thread for the assembly Effects of lubrication on torque Lubrication affects the torque value of any fastener assembly. Lubrication is often a matter of choice or company policy. If the assembly is fastened "for life," a lubricant is not critical. If the assembly is to be taken apart frequently, you should use a commercial anti-seize compound. Some manuals give a definite torque figure for lubrication and specific correction factors for common lubricants.  Table 5 contains torque values for graded steel bolts up to I" diameter, both dry and oiled. Table 5: Suggested torque values for graded steel bolts up to 1" diameter ~ Thread Dry Oiled Dry Oiled sizes ft.lbf N.m ft.lbf N.m ft.lbf N.m ft.lbf N.m '/4-20 8 9.8 6 7.64 12 19.6 9 9.8 '/4-28 10 9.8 7 9.8 14 19.6 11 9.8 5/16-18 17 19.6 13 19.6 24 29.4 18 19.6 5/16-24 19 29.4 15 19.6 27 39.2 21 29.4 3/9-16 31 39.2 24 29.4 44 56.8 34 49 3/8-24 35 49 27 39.2 49 68.6 38 49 7/16-14 49 66.6 38 49 70 98 54 69 7118-20 55 78,4 42 59 78 107.8 60 78.4 '/2-13 75 98 58 78,4 105 137 82 107.8 '/2-20 85 117.6 85 88 120 166.6 90 117.6 ·"6-12 110 147 84 118 155 206 120 166.6 9/16-18 120 166.6 93 127 170 225 132 176 5/a-l1 150 206 115 157 210 284 185 225 %-18 170 225 130 176 240 323 185 245 3/4-10 270 363 205 274 375 510 290 392 3/4-16 295 402 230 314 420 568 320 431 1/a-9 395 529 305 412 605 813 455 617 1/a-14 435 588 335 451 670 902 515 696 1-8 590 793 455 617 905 1225 695 941 1-14 660 892 510 686 1030 1392 785 1057 Chapter 6 Lubrication Kinds offriction.............................................................................. 6:1 Sliding friction.................................................................................. 6: 1 Rolling friction................................................................................. 6:2 Fluid friction..................................................................................... 6:2 Properties of oil.............................................................................. 6:3 Theories of adhesion and cohesion................................................... 6:3 Oiliness............................................................................................. 6:4 Viscosity.................................................................................... 6:4 Oi11ubrication................................................................................. 6:6 Lubrication using an oil wedge........................................................ 6:6 Boundary lubrication using an adherent film................................... 6:7 Hydraulic lock.................................................................................. 6:7 Additives and inhibitors................................................................... 6:8 Oil lubrication systems..................................................................... 6:9 Properties of grease........................................................................ 6: 13 Grease types...................................................................................... 6: 14 Grease lubrication........................................................................... 6:16 Choosing a grease............................................................................. 6: 16 Grease lubrication systems............................................................... 6: 16 Special oil and grease lubrication................................................... 6:18 Automatic lubricators....................................................................... 6: 18 Open gears........................................................................................ 6: 19 Enclosed gears.................................................................................. 6: 19 Oil and grease comparison............................................................... 6:20 Lubrication during cutting.............................................................. 6:21 Cutting oils....................................................................................... 6:21 Using cutting oil............................................................................... 6:23 Safe handling of lubricants............................................................. 6:23 Safety routine.................................................................................... 6:23 Safe storage and disposal.................................................................. 6:24  Lubrication Correct lubrication reduces friction between components and increases component life by reducing wear. Lubricants are substances (usually oils) used to do this. Kinds of friction The most carefully finished metal surfaee is not truly flat, but is covered with microscopic irregularities-projections and depressions as shown in Figure 1. These irregularities tend to interlock and resist sliding motion. Friction is the tendency to resist movement when surfaces are in contact as they move. Figure 1 Magnified finished