New guy here. We had a tornado come through our property in may and I've been trying to find a wheel loader to deal with all the trees. I don't have a lot of money so looking for older used stuff. I've been a mechanic all my life so not afraid of work but I certainly don't know the workings of all the different machines A guy has an older cat 920 that appears to be late 70s as far as I can tell. Owner doesn't know. What I do know is it runs, but it does not move. Owner said gear selector is stuck in fwd position. They tried to move it and it will not. From what I've learned, and please correct me if wrong, the E brake is automatically applied at the transmission when it runs out of air or is applied, won't release without air. Am I correct in assuming the transmission will not go into gear, until its shifted back to neutral? I havnt seen the machine, waiting to hear from seller but hope to go Thursday. Obviously I'm not buying it if it won't move. But I'd like to go with as much information I can get to find out if it has any life left in it. Lastly, I'm not a big brand loyal guy. Just need something that works that I can fix and get parts for.
Attached the operation of the transmission and air system/brakes. All the info you need to answer your questions should be somewhere in those two documents.
A Cat loader from that era should be pretty simple tech-wise and both OEM & aftermarket parts should be available.
Hey, thank you. Thats really cool. I read through that some but I'm still wondering about air. Clearly it needs air to release the E brake. Does it need air to shift or is that all mechanical? Or, is there anything obvious that would lock the gear shift lever? The owner got me the ser number (62K10887) so ill probably go see the dealer and maybe figure this thing out.
The machine dates from January 1980 BTW. See the diagrams and text on Pages 3 & 4 on the Air System/Brakes SysOp for machines with S/N 62K9973-Up, which obviously includes the one you are dealing with. "Depressing either the right or left service brake control valve pedal will apply the service brakes. However, depressing the left pedal will also send compressed air through transmission neutralizer line (1). This will release the transmission directional clutch and neutralize the transmission." So if either the left pedal treadle valve is passing air to the neutralizer line or if the neutralizer valve itself is stuck then the transmission will not engage any gear.
I used to have a 920. The E brake is air operated with a valve on the dash. Basically when the air pressure gets low the button on the dash pops out and sets the brake (similar to most semi trucks with air brakes). Sounds like the FNR lever is stuck in the forward position?? That is simply linkage down to the transmission. As far as I know the only thing that the transmission uses air for is when the left brake pedal is pushed it basically puts the transmission in neutral and applies the brakes as Nige said. The right pedal is brakes only. Clear as mud!!!
I'm following you. Trying to understand then, the neutralizer, does it require air to "de-neutralize"? I'm thinking that it didn't build any air pressure when he had it running.
No, it's the opposite. It requires air pressure to neutralize the transmission. So my thought would be to eliminate the possibility of an air leak in the left pedal treadle valve sending (unwanted) air to the neutralizer valve, or the neutralizer valve itself being stuck in the "oil pressure dump" position. Either of those possibilities would prevent the transmission building hydraulic pressure and not allow clutch engagement. You have to eliminate any possibility of the air system being the problem before moving on to the transmission hydraulic system. Once you have done that you have to consider the possibility that any sort of air leak in the suction side of the transmission pump could also result in no clutches engaging.
Gotcha. And thank you again. Just to be clear though. If the gear lever is stuck in forward.... Should it start in gear? If its started in gear, should it move? Or does it need to be put into neutral first, then fwd? The owner said the lever is stuck in fwd, but they had it running (maybe jumped starter?) But it wouldn't move. They tried to drag it and it won't move either, so assuming E brake holds and not building air. I'll try to get more info from him but I don't believe he knows much more.
There should be a neutral start inhibit function of some sort that prevents the engine starting if the transmission is in gear, or at least if the spools in the control valve are "not in neutral". It could be nothing more than a stuck shaft, pivot, or rod in the transmission control linkage. See the attachment.
I didn't think it should start in gear. But does it need to be shifted back to neutral and back to drive to move? I stopped at the dealer but the old guy who knows the old stuff wasn't there.
For a machine that is now well over 50 years old IMHO it is unrealistic to expect that all its systems will still work as designed or intended.
Well its all moot, just informed the guy sold it. Thanks for all the help, maybe there's another one out there.
I have to say, for all the machines I've considered, I'm most impressed with Cat and the Cat dealer. I want to thank you all for all your help. I'm sure ill be back with more questions if I find another machine. Hopefully something similar
The s/n of the 920 we had was 62K12538. So it was a little newer than this one. I'm 98% sure it would start with the lever in any position. If it was started in F or R it had to be cycled through neutral to get it to move. But like Nige said... It is a 50 year old machine so anything is possible.
I'm waiting to hear about another.
The one thing that can be said about Cat is that, no matter how old the machine, generally someone somewhere will have parts for it be they OEM or aftermarket. This contrasts sharply with the planned obsolecence practiced by many other manufacturers.
How about a 62K5672 ?? Looks tired but the man says it works. Do you put a 0 after K?
Do these 920s come with auxiliary hydraulics to run accessories like a grapple, or is it an option?
To get parts/service information, yes you do. I can't accurately date that particular Serial Number although it's obvious it's older than the other one you looked at. It was an option as far as I can see, so not all machines will have it.
Best I can determine its a 1974, but the guy says it all works. Bad time to be looking for equipment around here, everyone needs it. Even if i wanted something newer i can't find anything much within 500 miles.
The 920 we had for about 15 years was 62K6254. If I remember correctly it was a 1972
62K05672 shows as 1973 build in the book I have.
Well guys, out of more than a dozen wheel loaders, only three call backs. Two sold, the third the guys going on vaca.. I was at a guys place to look at something else and he had a 580c case. Its coming home Tuesday. I want to thank everyone for all the advice, sorry it didn't work out. If nothing else, hopefully it'll help someone else's decision, down the line.