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catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 2293
Experience:  Field service technician for CAT 19 years.
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Caterpillar 950 wheel loader 1970 model serial # 81J822 Will

Customer Question

Caterpillar 950 wheel loader 1970 model serial # 81J822
Will shift to neutral, first forward and first reverse but will not shift into 2nd, 3rd or 4th in forward or reverse. This happened at the same time the smaller of the two air lines coming from the air compressor rusted through. I fixed the air line but the shift handle will not rotate out of 1st gear
Submitted: 4 months ago.
Category: Construction and Road Equipment
Expert:  catmastertech replied 4 months ago.


Air compressor lines will not effect the transmission speeds. The only related part is a line from the left pedal to the transmission control valve to "de-clutch" the drivetrain when pressing the left brake pedal. This neutralizes the transmission but will not effect speeds or direction.

I would check the linkage for wear. Disconnect the shifter linkages and manually shift the transmission levers to see if the transmission will engage each gear. If you cannot move the levers on the transmission, the problem is internally and the transmission control valve may have a problem.

Also check the shifter for binding once you disconnect the transmission linkage.

You can usually access the linkage by removing the floor plate.

If you need further help, please let me know.

Customer: replied 4 months ago.
Perhaps it's that I have no clue other than a service manual which doesn't talk about shifting.I was able to twist the shift lever and shift gears when it was delivered. I am unaware of the left peddles affect on the transmission so maybe I just need basic instructions on how to use it as it has been 40 years since I drove one of these.
Expert:  catmastertech replied 4 months ago.

I am sure you already know the control pattern. The thing I see happen the most is the linkage get worn and jammed into some other object or the controls seize. Disconnecting the linkage is the best way to determine where the problem is located.

Disconnecting it at the transmission will show if the lever and linkage is the issue or the transmission control linkage and valves.

The left pedal is like the "neutralizer" pedal used today. On these older machines it required you to press the left pedal hard enough to force open the "de-clutch" valve and then the transmission is in neutral. This allows the engine power to be available for the hydraulic system and help the bucket break out of the pile quicker without you needed to move the lever. When youu left off the pedal, the transmission will re-engage the selected gear/direction.

If it appears damaged, see the attached files to correctly adjust the controls.

Customer: replied 4 months ago.
The control pattern? Twisting the shift lever to 1 through 4 is all I know. I'll try depressing the left pedal. If you can think of how someone with zero knowledge could fail in shifting or how I could do something to keep it from shifting please let me know. Seems like it shifted to nicely to all of a sudden that the shift handle won't twist at all.
Expert:  catmastertech replied 4 months ago.

Yes, that is what I meant. You already know how to engage forward and reverse and twist for each gear. Nothing else to explain on that.

You have not done anything wrong. Your machine has a problem. It is most likely in the shifter is damaged or the linkage is damaged. It could be in the transmission but, I have not seen that happen much.

That is why you must disconnect the linkage to figure out where to start. If you cannot find something obvious, at least you can tell where to focus for further repair.

Customer: replied 4 months ago.
I have not been able to address this issue yet so it's not yet time to rate your advice. I did just change out injectors and managed to strip out one of the fuel line nuts and I assume the part holding the injector that line / nut connects to. I'll have to try and find out where to buy those parts and then get back to the shifter issue. BTW the diagrams you provided show a second handle, mine only has one handle??
Expert:  catmastertech replied 4 months ago.

The instructions are for two different serial numbers. The service manual only states "early models" or "later models". I sent both to be certain you can see which will match your model.

Customer: replied 4 months ago.
I see now that diagram B14 shows early 950 and appears to have only one handle like mine.OK so the diagram doesn't give me enough info to imagine the relationship between the cap (#2) and (#5) rack and what the rack does. I did find the cap loose so I tightened it thinking it was just a tensioning nut, could operating the speed and direction control handle with the cap loose, then tightening the cap later have caused my issue of the speed control handle not being able to rotate out of first gear? If yes then how do I proceed?Thanks Arnold
Expert:  catmastertech replied 4 months ago.
The cap is just a cover. The adjustment is to allow the handle to rotate fully and engage all the speeds. The speed numbers on the handle are only for reference. It is an adjustable ring.
If handle rotates, use the adjustments to check your linkage.
Have you disconnected the linkage to find where yours is binding yet?
Have you tried manually moving the shift linkage on the transmission to see if it engages each gear yet?
Customer: replied 4 months ago.
The instructions say to remove the cap as if that did something. If it's just a cover then why remove it as they don't say to do anything under it right?I ran out of time yesterday, it's about 1.5 hours away. I had changed injectors and was preparing to look at the linkage and I ran it out of fuel. Then stripped out an injector line end and whatever the part is that the injector screws onto while bleeding out the lines. Any advice where I can find an injector line and the other part?After reading the instructions and noticed taking off the cap was needed I thought maybe that's were the problem started.
Expert:  catmastertech replied 4 months ago.

If you read through step 4 of the B-14 page, it states to turn the handle until the rack is 1.5 to 3.0 mm above the end of the housing then make adjustments to rod (6). The transmission linkage should be in fourth speed and if the rod is adjusted correctly, the linkage will fit properly.

Some customers add a small block on top the the rack (5) to block out fourth speed to control wild operators. If you remove the cap and turn it to fourth speed, the block will fall out. (if yours had one)

Your CAT dealer has a used parts section. That is were I source may parts for old iron when I am making repairs. Many of the engine parts are still available as new and prices are not that different from current machines.

I would never buy used injectors, only REMAN injectors from CAT so you can at least have a warranty.

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