American Friction Crane Boom down sticking

Has anyone had any issues with this? Or any ideas on how to fix it? Everything else is running pretty smooth

You should adjust that thing that caused it LOL

What in particular is sticking? Control lever? Brake band?

Does this unit have power down or do you have to slip it down on the brake? Had you looked at the line on the drum and made sure it wound on correctly?

The boom is power down, don’t need to use the brake. I’m actually the Oiler on this crane trying to help the operator. First friction crane I’ve worked on too. The cable is wound correctly on the boom. It was just inspected. It’s been sticking since the beginning. He’ll give it throttle for a while and it finally breaks loose after about 30-60 seconds and flys when it does.

One thing we do on stuck brake bands or one that won’t grip right is a little comet sprinkled on it. Seems to help them behave. I just did our old BE yard crane a few days ago. Sprinkle where you can and work it back and forth. Helps with the clutch too.

Sounds like the brake is not releasing fully. No you don't have power down, you have "power load lowering" meaning a sprag clutch on the mainshaft won allow an uncontrolled drop. Are you using less boom than normal? or is the brake band surface on the drum rusty? The band may be a bit tight with a short boom or a rusty drum may need to be burnished. Pick a test load and slip the brake down a few times to clean the rust off. Not a crane guy but have worked with plenty of hoists on drilling rigs.

Exactly what RZucker said.
It's a brake band adjustment and or dragging .
Could also be a galling sheave.
Tom

Another thing to check for is a dragging hoist up clutch, if its air controlled it may have a control valve leaking enough to create a slight drag on the clutch, that will give the same symptom.

RZucker said:

Another thing to check for is a dragging hoist up clutch, if its air controlled it may have a control valve leaking enough to create a slight drag on the clutch, that will give the same symptom.

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Had not considered that possibility, most all I worked were hard linkage. I was more inclined on the rusted drum.

Check the boom stops if its sticky at high angles,if they are a bit bent or rusty the boom will hang up.If you can boom down onto the ground try pulling line off the boom hoist by hand,if its running right you should be able to get slack off the drum even if you have to hang on the line a bit. Might also be low air pressure. Whats the main air gauge reading? You need a minimum 80 psi to boom down on the sprag. Get full air up ,shut the machine off and listen for leaks, try all the functions . You might be depleting the air with a blown booster on a swinger or hoist clutch.A weak compressor and bad leaks make for low air when you go to boom down ,you wont hear these leaks when your operating. If the boom is running away have the sprag checked/ replaced. What model is the crane? Last note note ,be sure your boom hoist cutout is functioning right. you should be able to stop the boom hoist while going up by manually pushing the paddle above the the boom hinge pin on the operators side of the boom.Americans [400/500 series for sure] usually bend the boom before the stops if the cutouts not working.

When was the last time the sprag clutch oil was changed ?, should be done annually!. After looking over what others have suggested check the oil in the sprag, if it’s low it will do exactly what your issue is , or if the fluid is old and gummed up, again it will do exactly as you described!.... This is an often overlooked service point on an American friction crane! And is well covered in the OP manual!...

Lee

Can anyone explain the reason they call for mineral oil in the manual . Its hard stuff to find around here. Not wanting to take a chance on any substitutions because of what the sprag does , i get mine from a friend that wrenches on helicopters .

Almost all 'Oils' are Mineral base, greases are or can be also mineral based but the added materials to make them a semi fluid Grease changes the behavior. In the 70s we used 90W Mineral Oil transmission fluid in a fleet I worked, where used a 85W90 Gear lube(Grease) in differentials. I would suspect has a great deal to do with Shear, fluid dynamics, fluid coating and lubrication quality where a Sprag need to drag in reverse rotation and slip in forward but not fry or go into metal displacement/exchange, a part of Shear qualification.