Question about brake cylinder chains

[cncproadwarrior]

I often see chains on the brake cylinders of some locomotives. What are they for? Do they just hook onto the body or do they go somewhere else. Did any SD40-2s and GPs have them?

 

[jbaakko]

The chain is pulled tight by the brake wheel, which activates the manual brakes.

 

[UP2CSX]

Also, as a very general rule, only SD type locomotives had a chain assist, attached to the front brake cylinder on the fireman's side of the engine. The chain was to give mechanical advantage in setting the brake cylinders over the longer wheelbase of the C-C truck. The shorter wheelbase B-B trucks didn't need the chain. It was generally only the one truck that had the brakes set mechanically, and that was to prevent the engine from rolling free if the air system failed. This is a very general overview and varied from railroad to railroad.

 

[Trouble]

every loco i've seen has a chain connecting the handbrake to the brake cylinder on the same side as the brake. some are more prominent than others, but usually while setting the brake you can lean over the railing and see if it's tight. on every railroad i know of, handbrake application is 100% on all engines that are left alone. basically the handbrake is like a winch. you turn the wheel or lift the ratcheting handle and it wraps up a chain, which is attached to a brake cylinder. as the chain tightens, it pulls the brake cylinder out and tightens the brake. usually you will see the chain hanging under the side sill near the handbrake, with a spring hangar to keep it suspended

http://img156.imageshack.us/i/sd40t204fm4.jpg/

you can see the chain, running from under the engine to a pulley wheel on a bracket. it then runs towards the rear of the unit, where a large spring keeps tension on the chain and keeps it on that pulley. the chain then sags and connects to the brake cylinder.

 

[MGWSY]

Just about every loco has a chain from the handbrake to the Brake Cylinder even though on some locos the chain is behind the sideframe and pulls the brake cylinder lever from there. Typically only 1 wheel of 1 axle has the handbrake applied which isn't much and I have had units roll away from me when coupling to them when a loose brake was applied and the air bled off.

 

[UP2CSX]

My answer was poorly worded. As you say, Mark, all locomotives have chains connected to the brakes cylinders. The ones on SD's are visible because the longer length of chain increases the mechanical advantage when setting the brake cylinder, which is a longer run than the chain from a B-B locomotive. Since the chain is shorter on a B-B, it's usually hidden by the frame. I didn't realize the hand brake only set one axle though. I thought it was all the axles of the truck. No wonder there have been so many roll-away accidents.