Mid 70's 40ton P&H. Working on blowing the cobwebs out of this thing and turning it into a useful piece of equipment. Yesterday I started braking the boom down in order to get it moved over to the shop. Once we got it down to the boom heel, went to boom down into the transport cradle, and it wouldn't do it. I got boom up, and even when I push the boom control lever for boom down, it booms up. Had this problem when I first got it, hung the main hook block off the boom heel and that was enough weight for boom down to work. Tried that yesterday and added two, 200lbs balls, no difference, still only booms up. When I shut the crane down for the day; with the machine dead, I set the boom dog, and moved the boom control lever for boom down. Boom hoist payed out a little and stopped by the dog. So what do the experts think? More weight tip on boom or some other issue? All other functions work great, but boom down has always been a little temperamental even with boom assembled. Picture shows me hanging one of the 200lbs balls, nobody call OSHA, it wasn't as bad as it looks.
No expert here, but it sounds like you have sticky clutches, Shoes or Discs? The boom heel doesn't put a lot of weight on the line to the drum, so a bit of clutch drag will keep it from going down. Next time don't dog it just shut down and let it out. When you have all the boom connected it should clear up unless the clutch is packed full of greasy goo.
It's got shoes all around. I guess more weight is the ticket, there already probably close to 1000lbs on there already. Granted that's nothing compared to the load the hoist would see at a 100% lift, but I wanted to double check before I started adding more. It's got power boom down, so with the engine dead I don't think it will let the boom winch pay out very far.
I think rz has got it for you. The boom should be just gravity/free fall down, but if the clutch is hanging up a little, it would go up with the boom down lever like you're describing. You don't need more weight, as much as you need to get the clutch adjusted right. When it has the boom on it, there is enough resistance/ weight to "slip" the clutch. Without the extra weight, it drags/grabs enough to raise the boom. If you're just setting it in the rest, you can shut down the engine, like rz said, and just use your brake to slow it down into the rest.
That would work, but I have no brake on the boom. Just the boom control lever, I have foot brakes for the two main winches, but not for the boom. And yeah, your right about needing to adjust the boom clutch. Wish I have some literature on it, but seems to be hard to fine stuff about old P&H's.
Does your machine have a torque convertor or a Rockford type clutch on the engine? Recheck your boom hoist drum, I'm betting it has a brake. Power down is not having the drum shove rope out to lower the boom, It's a sprag clutch on the mainshaft that only allows the drum pay out line as fast as the mainshaft allows. So it could be the torque that's hanging you up too. When you get multi part lines with no weight on them ... odd stuff happens. Got a customer with a 150K LB well service rig using a Link-Belt hoist works, 8 part line with a 500Lb block, lifts 20' at a time. I can pull that block up by hand on the load line. If his clutch drags in the least the block is stuck at the top. Shut the engine down, release the brake and down it comes.
I second what RZucker said. But there's one other possible cause. If I remember right P&Hs of that era had hydraulic controls, with master and wheel cylinders just like the ones in a car. I remember there was constant brake fluid leaks, I am thinking maybe the slave cylinder is sticking? Or maybe the pins in the boom hoist friction need lubrication, and are not letting it disengage?
No torque converter, very stiff foot clutch. It does have a brake, but I have no control over it. It's actuated automatically with the boom control. Yup that's how it's set up. I checked the fluids, but i'll double check.
OK... How does the boom control run the brake? Pull back to lift, and push forward to lower? Hydraulic control both directions? You should have control of that hoist brake in one way or another.
Running on memory right now, so this may be all wrong. Pull the boom lever back (boom up), brake releases and clutch applies. Push boom lever forward, brake releases and also releases a dog. Not the boom dog, that's separate. This dog releases when booming down otherwise it's engaged all the time. I'll try to get a picture of this so it'll make more sense.
That is making sense now. One lever control.
Yup, with clutch and brake tied together.
So that dog is like a overrunning clutch, it will allow boom up but not boom down. If you're power boom down, how is it switching directions?
When booming down that "overrun clutch dog" releases, and so does the brake. Never really understood what power boom down meant, but what RZrucker said (and it makes sense), power down just keeps me from booming down too fast. Everything else on this machine is simple as dirt, only the boom hoist is kinda confusing and gives me trouble. Next need to find out how the clutches are supposed to be adjusted. Super easy to adjust them, I just would like to know how tell they are set right.
You have most of it right. The overrun clutch slips when you boom up, and locks the drum to the mainshaft when you boom down. There should be an idler gear between the overrunning clutch gear on the mainshaft that allows for reverse rotation to boom down. A lot of older machines that had power load lowering had linkage to disconnect that idler for free drop applications like draglining. Also in your case when you are setting the boom heel in the rest, you can use the foot clutch to release the mainshaft to allow freedrop when you release the brake.[/QUOTE]
[/QUOTE] Thanks, I'll give that a try and see what happens.
Your boom hoist clutch is a little to tight sounds like, pull the seat out and lay down in there and check the clearance between clutch and drum all the way around. If its to tight you wont be able to knuckle it in, the lever that is but it does take quiet a bit of force too. same thing on the boom down side, have someone push on the lever and see if the brake is releasing you can see it move just a little, don't forget those dogs down there their is 2of them they have to be free sliding on the shaft that they ride on or they wont work they catch the planetary drum when you boom down, I'm not talking about the manual dog you'll see them while your down there looking, Help any way I can, take care and be care full, DW Also last thing we always did was lower the rear gantry after the boom dismantled
here is your planetary boom hoist drum
Yeah that does help thanks.
Just looked at this thread. Someone mentioned lowering the gantry. A old 30 ton P & H a bridge outfit I worked for used back in the day had to have the gantry down before it would lower the boom stub also. The clutch hung up enough to keep it from lowering. Back it off a bit it and it would slip with the boom in. The leverage change with the gantry down allowed it to lower. It was also a very well used/worn machine.
Thanks, the gantry is still raised so that may be part of the problem.
At work we have a p&h 430 which is a 35 ton. When it sits for a while and you boom it up too steep it does the same thing. I hook the block to the outrigger box and give a little tension then it will boom down
That's a good point ryan . After a friction crane sets awhile and the drums fuzz up with surface rust they are " grabby" & cantankerous until ya shine them up with some use . Same way if they are wet or damp .
Kind of like the old Cat cable control units, wet foggy mornings were always interesting. Lift a can and it went right back down. 10-15 cycles would usually clear it up but not always.
As soon as this things gets move over to the shop it'll get used fairly regularly, should be able to keep the clutches shined and fix the little niggling things it needs. I'm just pretty cautions working on this thing and operating it as I have a healthy respect for the size mess this crane could make if something bad happened.
Absolutely RZ ! Good point bro !
So I'm not gonna say that i move slow, but 3 years latley and maybe in the next 6 months i'll be working on this beast again..... Boom still doesn't go down, but it's atleast parked in front of the shop on gravel. So some progress....
Most control problems on the P&H stem from the hyd system. My auto matic reaction when i run a P& H is to pump the lever at least twice to get what i need > Seems the whether its a 325Tc or a 9125
P&H equals Pump and Hope.
And please help when hope dosent work.