Hand Operated Chain Hoists Overview
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Questions and Answers

What is the primary difference between a crane fork and a C-hook?

  • Crane forks are fabricated from profiled plates, while C-hooks are made from rolled beam sections.
  • Crane forks are used for lifting palletised loads, while C-hooks are used for hollow loads.
  • Crane forks are generally more versatile, while C-hooks are typically designed for specific loads. (correct)
  • Crane forks are typically used in permanent lifting facilities, while C-hooks are used in temporary applications.

    • What is a common application for powered lifting machines?

  • As part of an excavation system.
  • As a standalone lifting device for highly specialized applications.
  • As part of a larger lifting installation, like an overhead travelling crane. (correct)
  • As a primary power source for construction equipment.

    • Which of the following is NOT a common type of power source for powered lifting machines?

  • Pneumatic
  • Steam (correct)
  • Electric
  • Hydraulic

    • What is the main function of a crane fork?

    <p>To lift heavy loads directly from a crane hook without the need for other lifting accessories. (A)</p> Signup and view all the answers

    Why are crane forks and C-hooks considered together, despite their design differences?

    <p>They both operate on the same principle of direct load lifting. (D)</p> Signup and view all the answers

    In what scenarios are hand-operated chain hoists commonly used?

    <p>When precise positioning of the load is crucial. (B)</p> Signup and view all the answers

    What is the primary purpose of the chain end stop on a hand-operated chain hoist?

    <p>To prevent the load chain from passing through completely. (C)</p> Signup and view all the answers

    How do advancements in material and manufacturing technologies influence hand-operated chain hoists?

    <p>They allow for the production of smaller, lighter, and more efficient hoists. (D)</p> Signup and view all the answers

    What mechanism transmits the power in a hand-operated chain hoist?

    <p>A hand chain and screw brake mechanism. (D)</p> Signup and view all the answers

    How are combined types of hand-operated chain hoists typically configured?

    <p>They are typically coupled with a purpose-made traveling trolley. (B)</p> Signup and view all the answers

    What is the primary function of the automatic brake found in modern hand-operated hoists?

    <p>To arrest and sustain the load at any position. (D)</p> Signup and view all the answers

    What is the difference between lower capacity and higher capacity hand-operated chain hoists?

    <p>Lower capacity hoists have a single fall of load chain, while higher capacity hoists have multiple falls of load chain. (A)</p> Signup and view all the answers

    What is the primary advantage of using a lever hoist?

    <p>It can function in a wide range of positions and angles. (A)</p> Signup and view all the answers

    What type of chain is often used in a lever hoist?

    <p>High-strength, fine-tolerance short link steel chain. (D)</p> Signup and view all the answers

    What is the function of the 'change-over lever' on a lever hoist?

    <p>To release the brake and allow the load chain to freely run. (B)</p> Signup and view all the answers

    What is the primary purpose of the 'chain end stop' on a lever hoist?

    <p>To stop the load chain from completely passing through the hoist. (A)</p> Signup and view all the answers

    What is a common alternative name for a 'jaw' or 'creeper' winch?

    <p>Lever hoist (C)</p> Signup and view all the answers

    What is a significant characteristic of 'jaw' or 'creeper' winches?

    <p>They can be used for both pulling and lifting applications. (B)</p> Signup and view all the answers

    What is the reason for the lower factor of safety when using a jaw or creeper winch for pulling compared to lifting?

    <p>The winch is designed to handle higher loads when pulling. (C)</p> Signup and view all the answers

    Which of the following is NOT a typical characteristic of a lever hoist?

    <p>It utilizes a gripping action on the wire rope. (C)</p> Signup and view all the answers

    What is the primary function of the keys in a jaw winch?

    <p>To transfer effort from the levers to the jaws. (B)</p> Signup and view all the answers

    Why is it essential to use only manufacturer-approved ropes with a specific jaw winch?

    <p>To ensure the rope's diameter and construction can withstand the jaws' force. (C)</p> Signup and view all the answers

    What happens if a rope with a diameter that is too small is used with a jaw winch?

    <p>The jaws will not grip the rope sufficiently, potentially causing the load to slip. (C)</p> Signup and view all the answers

    What is the purpose of the tapered and fused end of the load rope in a jaw winch?

    <p>To facilitate easy insertion into the winch mechanism. (B)</p> Signup and view all the answers

    What is the primary function of the non-return valves in a hydraulic jack?

    <p>To regulate the flow of oil to the lifting ram. (D)</p> Signup and view all the answers

    What happens when the oil in a hydraulic jack is forced through the non-return valves?

    <p>The lifting ram is forced out of the chamber, lifting the load. (C)</p> Signup and view all the answers

    How is the load lowered in a hydraulic jack?

    <p>By opening a valve that allows oil to return to the reservoir. (B)</p> Signup and view all the answers

    Which of the following materials is NOT commonly used in the manufacture of hydraulic jack bodies?

    <p>Bronze (D)</p> Signup and view all the answers

    In which type of mechanical jack does the operator directly carry the load during the jacking operation?

    <p>Ratchet jack (A)</p> Signup and view all the answers

    What type of mechanical jack utilizes a bevel gear and screw mechanism?

    <p>Journal jack (C)</p> Signup and view all the answers

    What is the purpose of the pawls in a ratchet jack?

    <p>To engage the rack and raise or lower it. (B)</p> Signup and view all the answers

    What is the purpose of the swivel head in a screw jack?

    <p>To support the load. (B)</p> Signup and view all the answers

    What is the function of the running nut in a journal jack?

    <p>To raise or lower the lifting journal. (A)</p> Signup and view all the answers

    What is the difference between a ratchet jack and a screw jack?

    <p>Ratchet jacks use pawls and a rack, while screw jacks use a single screwed shank. (A)</p> Signup and view all the answers

    Which of the following is NOT a type of mechanical jack mentioned in the text?

    <p>Hydraulic jack (C)</p> Signup and view all the answers

    Which type of mechanical jack can have the full rated load supported either on the head or toe?

    <p>Ratchet jack (A)</p> Signup and view all the answers

    Flashcards

    Crane Forks

    Devices used to lift palletized loads directly from a crane hook.

    C-Hooks

    Hooks designed to lift hollow loads like pipes or coils from a crane hook.

    Powered Lifting Machines

    Electric or pneumatic devices used in industrial lifting operations.

    Electric Operation

    Lifting machines that use electricity for powering their lifting mechanism.

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    Temporary Lifting Facility

    A lifting setup used for short-term or specific lifting needs.

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    Mechanical Jacks

    Devices used for lifting heavy loads through mechanical means.

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    Ratchet Jack

    A type of mechanical jack using pawls and a rack to lift loads.

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    Pawls

    Mechanical components that engage with a rack to hold position when lifting.

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    Rack

    A bar with notches that interact with pawls in a ratchet jack.

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    Screw Jack

    A jack consisting of a threaded shank and a swivel head for lifting.

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    Swivel Head

    The part of the screw jack that supports the load and pivots.

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    Journal Jack

    A type of jack that uses a bevel gear and screw mechanism for lifting.

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    Bevel Gear

    A gear that allows the journal jack to convert motion for lifting.

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    Jaw Winch Operation

    Jaw winches operate using levers acting on keys to grip rope.

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    Components of Jaw Winch

    Includes jaws, lever system, and rope for operation.

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    Rope Diameter Importance

    Correct rope diameter is crucial for the grip and efficiency of jaw winches.

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    Manufacturer Approved Ropes

    Only ropes approved by manufacturers should be used with jaw winches.

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    Hydraulic Jack Materials

    Hydraulic jacks are made from aluminium, steel or cast iron affecting performance.

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    Hydraulic System Function

    Oil is used to lift loads in hydraulic jacks through non-return valves.

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    Lifting and Lowering Mechanism

    The load is lifted by oil pressure and lowered by valve operation allowing oil return.

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    Hydraulic Ram

    The lifting ram in hydraulic jacks moves up when oil is delivered underneath it.

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    Lever Hoist

    A manually operated tool for lifting and pulling that utilizes a lever mechanism.

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    Versatile Tool

    A tool capable of performing multiple functions in various orientations.

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    Adjustable Sling Leg

    Part of a lever hoist used to balance loads during lifting or pulling.

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    Types of Lever Hoists

    Two variations include calibrated short link steel chain and roller chain hoists.

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    Pocketed Wheel

    A wheel in a lever hoist that guides the load chain during operation.

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    Hand Chain

    A chain pulled by hand to operate the lever hoist.

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    Creeper Winches

    Winches using a gripping action on wire rope for lifting and pulling applications.

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    Working Load Limit

    Maximum load that a lifting device is rated to safely handle.

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    Manual Chain Hoists

    Mechanical devices used to lift loads manually via a chain mechanism.

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    Applications of Chain Hoists

    Used in permanent or temporary installations where power supply is unavailable.

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    Pocketed Wheel Function

    A wheel designed to accept load chain while allowing it to move freely in and out.

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    Automatic Brake Mechanism

    Safety feature that halts and holds the load at any position during use.

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    Single Fall Hoists

    Hoists with a single length of load chain lifting lighter loads (e.g., 500kg, 1t).

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    Multiple Fall Hoists

    Hoists designed with multiple chains for lifting heavier loads with increased capacity.

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    Combined Hoists

    Hoists often coupled with travelling trolleys for flexible movement along a support structure.

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    Study Notes

    Hand Operated Chain Hoists

    • Manual chain hoists are common globally, useful in various applications, including:

      • Permanent installations for infrequent use
      • Temporary setup for erection/maintenance
      • Precise load positioning
      • Where power isn't available

    • Technological advancements resulted in smaller, lighter, and more efficient hoists.

    • Hoist operation involves a pocketed wheel for the load chain to freely enter and leave, and a mechanism of hand chain and screw brake to drive the wheel.

    • A chain stop prevents the load chain from falling.

    • Modern hoists have automatic brakes, halting and holding the load at any position.

    Attachment

    • Hoists come in suspended or combined unit models.

    • Suspended hoists use attachments (like hooks, shackles, eyebolts) to be hung, offering varied articulation.

    Lower Capacity Hoists

    • Lower capacity hoists (e.g., 500 kg, 1 ton) lift the load using a single load chain.

    Higher Capacity Hoists

    • Higher capacity models may feature larger frames or multiple load chain falls.

    • Some high-capacity hoists include multiple frames linked via a yoke.

    Hand Operated Lever Hoists

    • Lever hoists provide versatile lifting and pulling capabilities for rigging and balancing loads.

    • They come in different types, utilizing either calibrated short link steel chain or roller chains for operation.

    • Advances in materials facilitate smaller, lighter, improved models.

    • The pocketed wheel, driven by a hand chain and screw brake mechanism, is a key feature.

    • A change-over lever sets the chain length.

    • A chain end stop avoids load chain passage.

    Lifting and Pulling Machines - Using Gripping Action on Wire Rope

    • Jaw/creeper winches are used for lifting and pulling in various situations, often with temporary or permanent rigging applications, potentially with a lower safety factor for pull-based work.

    • These are commonly manual, though hydraulic versions are also available.

    • Hydraulic versions often rely on link to an external hydraulic pump.

    All Jaw Winches

    • Jaw winches use levers and cams on keys to grip or release wire rope for operating.

    • The rope diameter is critical for effective operation; ropes must match the winch's specifications to ensure efficiency and safety.

    • The rope should be as integral to the winch mechanism as a chain is to a chain hoist.

    • Load rope entry is via a plain tapered section.

    Hydraulic Jacks

    • Hydraulic jacks are commonly made of aluminum and steel/cast iron; material selection influences design, weight and capacity

    • They rely on oil within the jack body or reservoir.

    • Hydraulic operation lifts/lowers the load by controlled oil movement through non-return valves into or out of the ram.

    Mechanical Jacks

    • Various mechanical jack types (ratchet, screw, journal) offer load lifting/lowering capabilities.

    • The specific jack parts and methods of operation slightly differ between the various types

    Crane Forks and 'C' Hooks

    • Crane forks and 'C' hooks lift loads directly without further attachments from crane hooks.

    • C-hooks are typically designed for specific loads.

    • Crane forks are typically used in more general-lifting situations.

    • The different types are often used in similar situations and can be grouped together when analyzing

    Powered Lifting Machines

    • Electrically or pneumatically operated lifting machines are widespread in the industry.

    • Their speed and reduced worker fatigue make them highly suitable, especially for repetitive tasks, that may require workers to be separate from the load.

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    Hand Operated Chain Hoists PDF

    Description

    Explore the functionality and applications of manual chain hoists in various settings. This quiz covers their operation, advancements, and types of attachments used. Understand the differences between lower and higher capacity hoists, including their mechanisms and safety features.

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