Vulcan Onshore Tip #65: Sheave Assembly Care

Proper care of the sheave assembly is very important, since the weight of the hammer is held by this assembly and a flying sheave or falling hammer could strike a person causing severe injury. Sheaves, axles, pins, keys, nuts, and all lifting points should be continuously checked for worn, loose or missing parts.

Check all cotter, roll and sheave pins for their condition and tightness and replace when worn or broken in service. Make sure that the correct type of pin (cotter or roll) is used with the corresponding type of head sheave. If in doubt, after examining the diagrams at left, consult an authorized dealer or the factory. The sheave pin is both held in place and kept from rotating by the two cotter (or roll) pins on each side.

If the sheave pin needs to be replaced, insert the new sheave pin with the sheave key in the existing hole until the key is firmly against the wall of the cylinder head. Then locate and drill a sheave key hole in the sheave pin. Make the hole the same size as the existing hole and locate it so that both sheave keys are pressed firmly against the walls of the cylinder head. Make sure that when cotter pins are installed the legs are spread so the cotter pin cannot fall out during service.

Roll pins use their internal tension to stay in place. The head sheave bushing should not be removed unless it needs replacement. Consult your Vulcan Onshore Field Service Manual for bushing replacement. If the head sheave needs replacement, a new bushing is included with the new sheave.

Always pull the hammer straight up, not at an angle to its central vertical axis. Pulling the hammer at an angle could pull the sheave pin through the head, disconnecting the hammer and sheave wheel causing both to fall. Avoid the use of spud or H-beam leaders with air-steam hammers of this type.

Use only genuine factory parts with this assembly, as with any other parts of the hammer. The use of nails, welding rod or re-bar to substitute for cotter or roll pins should be avoided

Note: much of the information in this tip is taken from Vulcan’s User’s Guide to Safe Operation, which is featured in the Guide to Pile Driving Equipment.

This is a very important safety bulletin and users of Vulcan hammers should take note and follow its recommendations seriously.


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