The projection of buffer from the head should be within 600 mm to 635 mm as per maintenance requirements for side buffer assemblies.

The length of side buffer for CBC-equipped SLR (FV & LV) is maintained to 635 mm as per RDSO drawing no. SK - 98145 (Ref: Carrg. Dte/RDSO letter no. MC/BLB/CBC dtd 17.02.08).

No oil or grease should be applied on coupler internal parts as it can cause the lock to slide and lead to automatic uncoupling. Only dry lubrication as specified should be used.

As per APTA-RP-M-004-98 Para 2.3, knuckles, locks, knuckle throwers, knuckle pivot pins, rotary lock lift assemblies, and pivot pins should not be reconditioned and must be replaced.

The supporting device is fastened using four bolts M20x50 mm tightened to 510 Nm torque value, with thread locking agent recommended.

If the center mark is not visible above the washer, the generator van should be unloaded until such time the center mark becomes visible above the washer.

Washer should be placed on top of loco knuckle, bolt allowed to go down. The gauge should be positioned so washer rests evenly on loco knuckle and lower end of bolt touches top of coach knuckle. The center mark must be above washer.

A vertical restrictor (RDSO Sketch No. CG-10063) should be provided in CBC of front end of first vehicle when locomotives are not fitted with 'H' type coupler. It restricts vertical movement in both up and down directions.

The pivot pin must be inserted from the bottom of the coupler with the cotter pin hole visible above the top of the coupler head.

WARNING: The knuckle is free to move when the knuckle pin is removed. Exercise extreme caution that the knuckle is not moved before knuckle pin is installed, and always support with a jack.

Coupler height shall be adjusted by adding or removing shims from the bottom of the coupler carrier assembly when the vehicle is empty and at rest on a level track.

Coupler height should be 34 inches to 35 inches, with 34-1/2 inches preferred. Reference coupler height center of coupler to rail is 1105 mm (43.5 inches).

When checking coupler levelness by suspending a weighted string against the machined front face of knuckle, the maximum distance from front face to string should be not more than 1/4 inch.

If the front edge of the toggle is 1/8 inch or more forward of the rear corner of the knuckle tail shelf, anti-creep is unacceptable and the lock lift assembly must be replaced.

If actual measurement of anti-creep is desired, inscribe a line on top of toggle along rear face of knuckle tail shelf. The measurement at point C must not be less than 3/8 inch.

The coupler lock should be seated not more than 1/8 inch above the knuckle tail shelf, preferably seated on the shelf. If adjustment is needed, metal should be removed from guard arm side of lock.

The contour condemning limit gauge inspects the limit of contour slack, which has been set at 3/8 inch. The gauge must not pass between the front face of coupler head and pulling face of knuckle.

The gauge verifies that points A, B, and C seat on the knuckle and that point D does not touch or clear more than 1/4 inch. If not, replace the knuckle.

The contour maintenance gauge must pass through the contour with the knuckle fully closed and locked, seated against the front face of the coupler head.

This NO-GO gauge must NOT pass into the wing pocket or over the guard arm. If it passes, there is excessive wear requiring coupler replacement.

This GO gauge must pass (slide into) the wing pocket and over the guard arm. If it does not pass, there is vertical distortion requiring coupler replacement.

The aligning wing limit gauge (No. 32600 APTA gauge) is used to inspect for excessive distortion of the guard arm of the coupler head.

After closing and locking the knuckle with coupler centered, the clearance between operating rod eye and lock lift lever should be 1/8 inch to 1/4 inch on either side.

The knuckle pivot pin's original diameter is 1-5/8 inches. If worn more than 25%, replace the pivot pin and cotter pin.

Original diameter of the support pin is 5/8 inch. If worn more than 25%, replace the support pin and/or cotter pin.

A clear telltale slot with the rotary lock lift lever rib in vertical position indicates proper locking of the knuckle after coupling.

Partial locking where knuckles are locked but lock lift lever is not fully dropped is dangerous as it gives false indication of coupler locking. Such incidents should be taken very seriously, recorded, and reported to RDSO.

The front carrier plate has a hole of Ø110 mm for inserting the central pin which is Ø80 mm.

The position of central pin is secured by sliding the locking plate in between the central pin and front carrier plate, which prevents the pin from falling off.

The central pin (Ø80 mm) connects the coupler head linkage to the draft gear. It is inserted through the hole in front carrier plate from the bottom side of the underframe.

The correct sequence is: place Balanced Draft Gear on hydraulic trolley, raise until inserted in pocket, tighten wedge lock, then place and bolt the front and rear carrier plates.

The wedge lock must be tightened in a zig-zag manner up to 400-450 N-m torque during mounting of the draft gear in the pocket.

The original thickness of the coupler shank wear plate is 1/4 inch. When reduced to 1/16 inch, it shall be replaced.

The coupler shank is welded with a wear plate made of manganese steel in the supporting area, which is the contact area between the coupler shank and the coupler support device.

In muff coupling type couplers from Dellner and Faiveley, the coupler head and draft gear (draw bar) are joined through muff coupling, and articulation of the coupler head is through elastomeric pads, providing better riding behavior.

M/s Faiveley, M/s Escorts, M/s Sanrok, M/s Frontier, and M/s Voith produce couplers with integral shank and balanced draft gear design.

As per RDSO/2011/CG-03 (Rev.01), the draft gear dynamic capacity should be minimum 35 kJ. For Rev.03, it is 20 kJ min. and not exceeding 35 kJ.

As per RDSO/2011/CG-03 (Rev.03), the draft gear should be suitably pre-compressed with preload of 10 kN - 20 kN.

The torsional strength requirement for integral type shank coupler is minimum 135 kN-m, ensuring the coupler can withstand torsional forces during operation.

The balanced draft gear is a double-acting device for energy absorption, fitted into the draft gear pocket of the coach. It contains two separate elastomeric pad stacks - one for buff mode and one for tensile/draft mode, absorbing impacts in both directions.