Train Parting: Coupler Forces and Definitions

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Questions and Answers

What is the primary purpose of draft force in couplers?

It is needed for pulling an attached coupler or wagon. (correct)

It eliminates slack in the couplers.

It prevents the wagon from rolling backward.

It is required for pushing a wagon.

What does buff force signify in coupler operations?

Force required for pulling another attached wagon.

Force indicating the maximum slack in the coupler.

Force on the coupler required for pushing another attached coupler or wagon. (correct)

Force necessary to absorb impacts during draft.

What is slack in the context of draw-gear?

The maximum weight a coupler can handle.

Free play provided in draw-gear for movement around curves and grades. (correct)

The distance between two connected couplers.

The total length of a train's coupler.

How much free slack is typically allowed for a wagon?

1 inch Signup and view all the answers

What is the definition of run-in regarding train coupler slack?

Rapid change of coupler slack to buff (compressed). Signup and view all the answers

Which statement best describes run-out in train coupling?

Rapid change of coupler slack to draft (stretched). Signup and view all the answers

What is the function of the draft gear in a coupler system?

To absorb impacts and attach the draw-gear to a loco or wagon. Signup and view all the answers

What does the term 'spring slack' refer to?

The additional longitudinal movement after free slack is finished. Signup and view all the answers

In which situation does slack action occur?

When one part of a coupled train moves at a different speed than another. Signup and view all the answers

What is the total slack estimated for 40 vehicles?

20 feet Signup and view all the answers

What is a common consequence of improper brake application in freight trains?

Compressive coupler forces Signup and view all the answers

What key practice is advised to maintain a good train handling when applying brakes?

Ensure the consist is stretched Signup and view all the answers

Which of the following can be a reason for coupler failure?

Excessive wear on knuckle Signup and view all the answers

What is the designed ultimate tensile strength (UTS) of the CBC coupler?

295 T Signup and view all the answers

What can lead to train parting due to coupler issues?

Uncoupling lever dropping during motion Signup and view all the answers

What action should be taken to reduce the chances of train parting while starting from a standstill?

Back the train a little Signup and view all the answers

A primary factor influencing the severity of run-in after brake application is:

Force and slack distribution Signup and view all the answers

What can result from improper use of dynamic brakes during train handling?

Severe slack action Signup and view all the answers

Which factor does NOT contribute to poor tensile strength of couplers?

Proper heat treatment Signup and view all the answers

Which of the following practices can help prevent train partings due to uncoupling?

Ensuring lock engagement is secure Signup and view all the answers

What is the primary cause of wear and fatigue in couplers during operation?

Repeated impact forces between wagons Signup and view all the answers

What happens to the wagons as the locomotive climbs the grade?

They slow down and begin to compress Signup and view all the answers

What is described as the natural frequency of the train?

The oscillation pattern following a compression Signup and view all the answers

Which driving strategy helps in controlling longitudinal coupler forces?

Taking up slack in the couplers gradually Signup and view all the answers

What is one of the consequences of slack being taken up between large groups of wagons?

Increased risk of train parting Signup and view all the answers

During what situation are maximum chances of train parting most likely to occur?

While negotiating undulating graded sections Signup and view all the answers

What precaution can help avoid excessive coupler forces while climbing a grade?

Manipulating power slightly and coasting Signup and view all the answers

What should be done just before approaching the top of the hump to avoid excessive speed?

Reduce power slightly Signup and view all the answers

What occurs when the slack between two blocks of wagons is fully used up?

A wave of compression causes oscillation Signup and view all the answers

What impacts force causes coupler breakage?

Square of the difference in speeds of the wagons Signup and view all the answers

What is the consequence of not allowing time for brakes in rear wagons to fully release before further notching up?

Potential for excessive stress on the coupling mechanism Signup and view all the answers

Which component of the coupler is NOT recommended for lubrication at any stage?

Lock Signup and view all the answers

What should be checked to ensure proper functionality of the couplers?

The presence of unauthorized tampering Signup and view all the answers

What type of hardening process can be applied to the wearing surfaces of the knuckle to reduce wear?

Plasma weld deposition Signup and view all the answers

What is one method proposed to prevent unauthorized tampering with the uncoupling mechanism?

Installation of a locking arrangement Signup and view all the answers

Which defect may indicate a need for a wagon to be marked sick?

Excessive dropping of the coupler Signup and view all the answers

What should be strictly adhered to during the procurement of coupler spares?

Quality assurance Signup and view all the answers

Which of the following items should be sent for reclamation if they show signs of wear?

Draft gear components Signup and view all the answers

During the inspection of the operating mechanism and rotary lifting gear, what conditions should be closely monitored?

Presence of bent rods and broken brackets Signup and view all the answers

At what stage should the anti-creep feature be checked on all wagons?

Before leaving the sick line Signup and view all the answers

What is the primary difference between draft force and buff force in train operations?

Draft force requires complete compression before pulling, while buff force requires complete extension before pushing. Signup and view all the answers

In the context of couplers, what does 'free slack' specifically refer to?

The slack that can be taken up without engaging the draft-gear. Signup and view all the answers

What is the value of spring slack when draft-gear is fully pressed?

5 inches Signup and view all the answers

During which scenario is run-in most likely to occur?

When a rear section of a train moving faster collides with a slower-moving front. Signup and view all the answers

Which term describes the rapid change of a train’s coupler-slack to draft due to acceleration?

Run-Out Signup and view all the answers

What does 'slack action' entail in a coupled train system?

Differential movement between coupled units, resulting in changes of slack. Signup and view all the answers

What is the maximum total slack estimated for 40 vehicles in a train?

20 feet Signup and view all the answers

Which component interacts directly between a loco and a wagon?

Draft Gear Signup and view all the answers

What is the implication of having improper slack conditions between train wagons?

Increased risk of train parting during operations. Signup and view all the answers

What is one of the main purposes of providing slack in draw gear?

To allow movement around curves and grades. Signup and view all the answers

What method should NOT be used for lubricating coupler components?

None lubrication Signup and view all the answers

What is a required step in the procurement of coupler spares?

Conducting rigorous purchase inspections Signup and view all the answers

Which issue signifies that a wagon should be marked sick?

Excessive dropping of the coupler Signup and view all the answers

What action should be taken regarding the operating mechanism of couplers?

Examine for any bent rod or broken bracket Signup and view all the answers

What should be strictly avoided in regards to the coupler's locking arrangement?

Ensuring easy access to the uncoupling gear Signup and view all the answers

Which of the following practices is encouraged for maintaining couplers?

Allowance of time for brakes to release fully Signup and view all the answers

What is a recommended method for enhancing the durability of coupler components?

Applying a Plasma weld deposition process Signup and view all the answers

What should be done to components that are reclaimable regarding couplers?

Send them to workshop for reclamation or rejection Signup and view all the answers

What is required for the heat treatment of coupler components?

Proper heat treatment procedures to be followed Signup and view all the answers

What is an essential maintenance practice for ensuring proper coupler function?

Regularly checking the anti-creep feature on all wagons Signup and view all the answers

What effect does uneven loading of wagons have on brake application?

It leads to differential braking behavior among wagons. Signup and view all the answers

Which of the following is NOT a consequence of using dynamic brakes improperly?

Excessive cargo shifting Signup and view all the answers

What is a potential reason for coupler failure related to manufacturing defects?

Presence of casting defects or blow holes Signup and view all the answers

Which practice can help minimize the risk of train-parting due to uncoupling?

Ensuring the lock is properly engaged Signup and view all the answers

What is one of the key precautions to take when starting a train from a standstill?

Back the train a little before proceeding. Signup and view all the answers

Which of the following factors most significantly influences the severity of run-in after brake application?

Force and slack distribution prior to application Signup and view all the answers

Which issue is a consequence of improper heat treatment of the knuckle?

Reduced ultimate tensile strength Signup and view all the answers

What does not contribute to coupler failure among the listed options?

Regular maintenance checks Signup and view all the answers

Which condition is likely to lead to a run-out when dynamic brakes are released inappropriately?

Releasing brakes while navigating a curve Signup and view all the answers

What factor can lead to ineffective anti-creep devices and its consequences?

Inappropriate coupler alignment Signup and view all the answers

How do longitudinal coupler forces typically arise in a train during movement?

They occur when two groups of wagons move with different speeds due to slack. Signup and view all the answers

What is the consequence of managing slack action on a single wagon in a long train?

It can lead to higher forces at the points of coupling. Signup and view all the answers

What do high impact forces in a train result from?

Relative rapid movement of rear wagons into slower front wagons. Signup and view all the answers

In what scenario are maximum chances of train parting highest?

While negotiating undulating grades with high slack. Signup and view all the answers

What precaution can help limit excessive coupler forces on a graded section?

Manipulate power judiciously and coast down gradients. Signup and view all the answers

Which driving strategy can effectively limit the forces acting on couplers?

Controlling slack action progressively across multiple wagons. Signup and view all the answers

What happens when slack is fully taken up between two separate blocks of wagons?

Longitudinal coupler forces may exceed permissible limits. Signup and view all the answers

What impact does the natural frequency of oscillation have during the run-in phase?

It influences the speed of oscillation throughout the train. Signup and view all the answers

What is the effect of using severe braking on the train just before a dip?

It causes undue strain on the front couplers. Signup and view all the answers

How do undulating grades affect the behavior of train wagons relative to coupler forces?

They may lead to potential loss of control over longitudinal forces. Signup and view all the answers

Study Notes

Train Parting: Types of Coupler Forces

Draft Force: The force needed to pull one attached coupler/wagon. Pulling begins after complete coupler extension.
Buff Force: The force needed to push one attached coupler/wagon. Pushing starts after complete coupler compression.

Train Parting: Definitions

Draw Gear: The coupling mechanism between locomotives and wagons or between wagons.
Draft Gear: The impact-absorbing components attached to the draw gear of the locomotive or wagon.
Slack: The free movement in the draw gear (or part of it). Required for movement around curves and grades, with free play. Ranges up to 1 inch for wagons.
Spring Slack: Additional movement after free slack. It occurs after the free slack movement is finished, when the drawgear is compressed or rebounds; directs all slack in the opposite direction, values are up to 5 inches. Total slack for 40 vehicles is about 20 feet.
Run-In: Rapid change in coupler slack from stretched to compressed when the rear of a train travels faster than the front, usually from sudden braking.
Run-Out: Rapid change in coupler slack from compressed to stretched when the rear of a train travels slower than the front, usually from sudden acceleration.
Slack Action: Movement of one part of a train at a different speed than another part. Impact force from bump on couplers is related to the square of the speed difference, causing wear and fatigue, and possibly coupler breakage.

Train Parting: Run-In/Run-Out Mechanism

Run-In Mechanism: Occurs when a train climbs a grade. The rear of the train slows down and compresses as the front runs into it. The compression continues until a wave reaches the rear of the train, causing oscillation.

Train Parting: Driving Strategies

Controlling Slack: Crucial to limit longitudinal coupler forces. Low forces occur when slack is taken up one wagon at a time; however, this is not suitable for long trains. Preventing relative movement of large wagon groups is important as high forces result in bunched or stretched wagons moving together (or apart). Run-ins and run-outs happen when slack is used up, leading to excessive forces.
Driving Precautions: Maintaining consistent speed with MP manipulation and coasting where possible to reduce power before grades or dips, and also avoiding sudden braking.

Train Parting: Train Brake Application

Brake Application Impact: Brake application causes compressive coupler forces. Severity depends on the force and distribution of slack previously within train, as wagons may not brake equally. Keeping train consists stretched while applying brakes reduces risk. Using dynamic brakes may cause severe slack action if applied improperly (with respect to track geometry and train speed) causing unwanted run-outs.

Train Parting: Coupler Maintenance

Coupler Failure Causes: Causes of broken couplers include excessive & uneven wear on the knuckle and plates, and poor heat treatment.

Train Parting: Uncoupling and Precautions

Uncoupling Reasons: Lock not properly engaged, ineffective anti-creep device, uncoupling lever dropping, unauthorized tampering with uncoupling lever, or uncoupling due to vertical slipping of the knuckle.
Precautions: Starting the train from standstill, slowly. Avoiding sudden notching up; sudden brake application from rear of train; and keeping the couplers in a stretched slack condition. Employing proper casting and maintenance of couplers for better quality.

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Description

Explore the essential concepts of coupler forces involved in train parting, including draft and buff forces. Understand the definitions of draw gear, draft gear, slack, and more. This quiz will enhance your knowledge of railway coupling mechanics.