Old Cat telehandler RT100 questions

[thomas53]

I recently bought an older (90's) cat RT100 telehandler. (Cat RT80 also has similar parts)
Put it in a shop to rebuild a hydraulic cylinder. That was done and the shop called and said that the machine stopped working and that joystick control was bad.
Got no help from Cat - they say the parts are discontinued and basically to buy a new machine.
Checked internet to try to find the part - seems like 1 is available somewhere but thru 1 company, they want almost $5,000 for it. Another place wants almost $7,000.
That's nuts. Especially when most other joysticks are between $65 and $500 to buy.
joystick is Caterpillar part number 126-1168. It's made by Penny Giles. Anyone know the Penny Giles part number for this?
Tried a number of joystick rebuild companies. They all say contact CAT - been there, done that.
The rebuild shops said they don't have schematics to test the boards in the joystick to perform any repairs.
No one will touch it.
My questions - Does anyone know how to retrofit the joystick on these machines? Is there a drop in easy replacment joystick?
Can I change other things on the machine to make a new joystick system?
if the motor and everything else on the machine wasn't good, I wouldn't bother trying to do a retrofit.
Anyone got any ideas?

 

[Mark250]

have you confirmed the joystick is bad?
have you checked the basics like fuses?
Cat have changed this to a pilot operated control and I have the info if you need it
Mark

 

[thomas53]

The shop said the joystick was bad because nothing was operating anymore - the boom wouldn't raise or lower, etc.
In taking the joystick apart, I can see where the cracked rubber boot had allowed water into the joystick ( lots of rust came out of the can) and figured maybe something shorted. No way to confirm as don't have anything to plug back in to check and no one seems to be able to test the joystick ( had contacted many electronic joystick repair shops).
Would love to know where a fuse is so I can check it my self and change it out

 

[Mark250]

 

[thomas53]

Got it. Will check all fuses myself when I bring the joystick back to that shop on Monday. Hope that is the cause of the problem.
Will update this thread once I know.
Thanks for the input.

 

[thomas53]

Also, Can anyone tell me the actual specs and year of manufacture for this machine? - 1GJ00928

 

[Mark250]

build date 11/10/1993
just google and the spec come up

 

[thomas53]

All fuses look fine.
I hooked the joystick back in.
Side front button booms the unit out. Side back button does not retract boom.
Front right button - when pushed in, it looks like the boom is trying to raise but its like the fork is too heavy to lift ( nothing on it) or it doesn't get enough fluid to operate the cylinder ( fluid is full) or like it has a clamp or something holding the boom down - you can see the machine strain to lift it an inch or so.
Any ideas?

 

[Mark250]

I don't think I can help much further due to lack of information
but I will offer some observations and thoughts.
1/ As I said in an earlier post cat changed this system to a pilot operated system as out lined in publication REHS 0035 which is used in the TH series machines
2/ Joystick forward or backwoods movement should control the Boom raise and lower
3/ joystick left to right movement should control the fork or bucket dump or rack back (type 2 control layout)
(type 1 control layout joystick movement left to right controls boom extend and retract )
4/ The front two buttons on the joystick control the boom extend and retract function (type 2 control layout)
(type 1 control layout the two front buttons control fork or bucket dump or rack back)
5/ the side buttons on the joystick are for the aux functions if equipped ( type 2 control layout)
6/ looking at the schematic 2 outputs of the joystick are single wire signals which suggests to me that they are PWM or analogue outputs and you should be able to measure this with a digital multimeter.
this would give you an indication of the joystick condition
If you are measuring good signals from the joystick I would then check the duty cycle or voltage going to the solenoids on the hydraulic control valve
7/ It seems a bit strange to me that if the machine was functioning ok before it went into the shop there should be no reason why it is not functioning now unless it is something they did
8/ As they opened up the hydraulic system for the repair, has contamination gotten in the system to cause you problems
Mark

 

[thomas53]

The more I get into and learn about the machine, the clearer things are becoming to me.
From what I surmise, I think that when they opened the joystick, they broke 1 wire. For what function that single wire is for, I have yet to find out.
Am thinking boom retraction.
When I hooked up the joystick, there was 1 red indicator light on - am still trying to figure out what that is as the dash is extremely faded/fogged making it hard to see what it is.
I got the boom to extend out and the boom tried to raise up but after the slightest pressure, it was like banging against a wall to try to raise.
Either the machine has some kind of hydraulic lockout stopping the boom from raising or there is something mechanical pinning it from raising up.
It definitely is trying.
I now have the operator manual on my computer. Will take computer with me and try the functions and look for some kind of mechanical stop preventing machine from operating.
If you know of any lockout that as a safety device/function that disables the joystick, I sure would like to know about it and also a way to stop it from engaging.
Am also trying to get my hands on a service repair manual.
I intend to go from totally stupid into knowing this machine inside out by the time I am done.

 

[jimmycat]

I am wondering if Thomas53 got his telehandler working.We have a RT100 and it has a creepy boom.What I mean is that the boom will some times creep ahead in jerks without operator.Cat tells me it is joystick problem.Any suggestions/

 

[Custom Electronics]

Just found this forum looking for RT-80 information.
Well, I can share what I do have.
I have reverse-engineered the Penny+Giles joystick schematics and will share them with anyone who needs them.
I also can rebuild the joystick for a flat rate of $350 each, including a new boot.
Contact me at: kevin.counihan53@gmail.com
After the rebuild, you may need to run the joystick calibration routine internal to the onboard computer.
Usually, the board suffers severe corrosion from the torn boot and will require extensive cleaning.
Also the wires to the handle break at the pivot point inside the mechanism.

 

[CaptainCrane]

My Joystick for my Cat RT80 telehandler had failed and the dealer was no help. kevin.counihan53@gmail.com just completely rebuilt my Joystick and now the machine is working again. Joystick repair was on time and at the price quoted. Thanks Kevin.