Okay, its a 924g with ride control. The ride control seems to be a system to relieve pressure on the loader arms to control bouncing with a load. From reading in the book and running it, depending on how you have the ride control button set, the loader arms are able to a: absorb shock when over a certain mph, b: absorb no shock (system disabled) c: absorb the shock all the time (system override). From looking at it, it has some pressure accumulaters mounted underneath, and the book says if you set the switch wrong, damage can occur to the machine. I imagine this means running it with shock absorbing on all the time, and trying to dig. Since everyone and their dog has run the thing, I'm sure this has happened (One guy complained to me b/c he couldn't get the front wheels to pick off the ground with the bucket, he didn't even know what ride control was for). Now the problem: on picking up a item (we use it with a set of forks a lot) the loader arms will come up and as soon as the weight hits a certain amount (approx 2-3000lbs) the arms drop back down. Once it has fallen the 1st time, I can then pick it up. This may happen more than once a day, but its not all the time. I'm guessing problem with the pressure accumulators or cyl troubles. Help?
Can you explain "as the weight hits a certain amount"? Do you hold the forks off the ground and gradually add more load? What position is the ride control switch in when the problem occours? IF you have the switch set to "on" and you are gradually adding more weight to the forks, then they drop a little, it sounds as though the system is working OK but the accumulator is a little low on charge pressure.
It's most likely a problem with the ride control. We get this complaint pretty regularly at the dealership. The 3 position switch is great for smaller contractors or dedicated operator / machine outfits but can give fits to users who have lots of people on and off the loader. Cat Dealer in your area should be able to troubleshoot pretty quickly and tell you if it is something simple... like bad accumulators or even a solenoid failure in the switch that keeps ride control enabled. From what you are describing it doesn't sound like a hydraulic problem... you'd have a leaking cylinder or loss of pilot pressure, either of which would trip warnings. Hope this helps.
The 924,928 and 930's had a valve update on the ride control. Im not sure if your s/n is in there or your hours. If the valve failed it could have damaged somthing else. Call you local dealer and get them involved. If im right it should be free to you or cat will pick up around half of the cost. Im sure the local dealer would love to have the work these days. Hope this helps.
Thanks for the help guys. The weight is a guess when lifting. Meaning that I've usually got weight on the forks, just get a load of material picked up, and bang, down come the arms. Makes the operator look like a jack---. The arms won't do it with no load/forks, but the bucket itself is enough to make it drop. The arms will do it in any ride control setting, so its definetly not working the way its supposed to. I like to have a little idea what I'm talking about with the mechanic, and this is a great resource. Does anyone know exactly how the ride control works on this? I'm assuming there's a pressure relief, so much increase in arm hyd pressure and the cly releases, then the accumulators work as a cushion until the pressure goes down enough, the relief shuts and the cylinder holds again. Am I right?
There are 2 valves, the first one keep the accumulator charged with the same pressure as the cylinder. This is active all the time. it's called a shuttle valve (141-1481) Then the valve (297-1209)that the operator controls with the ride control button, it opens a passage between the acc and cylinder, so if it the acc isn't charged to the same pressure as the cylinder when it opens the arms may bounce up or fall down. There is a spring inside this that can break causing problmes of this type. Both valves are mounted on the rear frame below the acc Does it drop an inch or a foot? With ride off, can you lift the machine and it stays up?
Thanks per eriksson. The machine basically will drop until the weight comes off, it actually won't pick the load off the ground. Usually I can pick up on the load until its almost off the ground and then back down it comes, so no, it won't drop a foot, it actually only drops a few inches till its on the ground or trailer. With ride off it can pick itself and hold itself up with no problems. The dropping issue is only some of the time which is the frustrating part, I hate to have the CAT man come and then its working fine, then the mechanic looks at me and says "what am I here for?" followed by the boss asking "what is he here for?"
What serial is your machine, Cat made a big change to the ride system halfway through.