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D6c power shift issues.

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6 years 5 months ago #182608 by tnc110
Im having problems with mine. . It will pop out of gear and then you hear gears grinding , sounds like it's not fully in gear and /or in between gears. is there an adjustment that can be made or what's going on here? Power shift model. 10k series.

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6 years 5 months ago #182609 by tnc110
Replied by tnc110 on topic D6c power shift issues.
Update. Ran it for about an hour and never had a repeat issue. However now left-hand-drive gave out feels like there is a problem in the valve as there is no resistance when you pull lever versus the right hand side. Left side track has very slight power applied to it when engaged.

I let machine sit for a while and got on it again everything was fine. I only worked for a couple minutes and then the left rack went out again with no power.

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6 years 5 months ago #182618 by Old Magnet
Replied by Old Magnet on topic D6c power shift issues.
There aren't any gears to grind when shifting. All the gears are planetary type controlled by clutches. If there are problems with transmission shifting and steering clutches the first order check would be a pressure reading on the transmission pump.

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6 years 5 months ago #182620 by Wombat
Replied by Wombat on topic D6c power shift issues.
What condition is your transmission oil? Remove transmission filter(s) and magnetic screens and check for contamination and metal. Sounds like a pressure problem as OM has said, maybe other problems causing drop in pressures as well as a failed transmission pump.

Wombat

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6 years 5 months ago #182633 by OzDozer
Replied by OzDozer on topic D6c power shift issues.
tnc110 - You could have a problem with your steering control valve (SCV). This is the valve unit that sits on top of the steering clutch/final drive case, underneath the fuel tank. You will see the steering linkages attached to it.
There are springs inside the SCV spools that give the resistance to the steering levers. If you have no steering lever resistance on the left side, you have a broken spring in the SCV.

The "grinding" sound may have been clutch plates slipping with low pressure. For the transmission to pop out of gear, this means you're losing transmission oil pressure.
The oil pressure is supplied to both the transmission and the steering clutches from the transmission oil pump. If you develop a leak anywhere in the system, this drops the pressure for both the transmission and the steering clutches.

The transmission control valve is operated by the gear lever and this valve needs oil pressure to compress a big spring to allow gear and direction selection.
If the oil pressure to the transmission control valve drops, the big spring comes into action, and returns the gear lever to neutral to prevent transmission damage.

Another thing that can happen is if your bevel gear bearings start to collapse (there is a taper roller bearing each side of the bevel gear), then the bevel gear shaft will drop, and this chews out the square, piston-ring type seal, in the actuating piston that disengages the steering clutch.
You will generally then lose the ability to disengage that particular clutch. However, it is unlikely you could lose drive to that side, unless the disengaging piston has jammed and is holding the steering clutch disengaged.

You can find out if you have failing bevel gear bearings by removing the thin plate that covers the PTO hole on the centre of the rear upright face of the steering clutch housing, inserting a crowbar under the bevel gear shaft and prying in an up-and-down motion. There should be no movement at all in the shaft. Serious amounts of movement indicate a failed bearing - and major back end repairs.

Of course, if a winch or any PTO-driven equipment is fitted, you will need to remove that, to access the bevel gear compartment.

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6 years 5 months ago #182651 by tnc110
Replied by tnc110 on topic D6c power shift issues.
Great info. Thank you!

tnc110 - You could have a problem with your steering control valve (SCV). This is the valve unit that sits on top of the steering clutch/final drive case, underneath the fuel tank. You will see the steering linkages attached to it.
There are springs inside the SCV spools that give the resistance to the steering levers. If you have no steering lever resistance on the left side, you have a broken spring in the SCV.

The "grinding" sound may have been clutch plates slipping with low pressure. For the transmission to pop out of gear, this means you're losing transmission oil pressure.
The oil pressure is supplied to both the transmission and the steering clutches from the transmission oil pump. If you develop a leak anywhere in the system, this drops the pressure for both the transmission and the steering clutches.

The transmission control valve is operated by the gear lever and this valve needs oil pressure to compress a big spring to allow gear and direction selection.
If the oil pressure to the transmission control valve drops, the big spring comes into action, and returns the gear lever to neutral to prevent transmission damage.

Another thing that can happen is if your bevel gear bearings start to collapse (there is a taper roller bearing each side of the bevel gear), then the bevel gear shaft will drop, and this chews out the square, piston-ring type seal, in the actuating piston that disengages the steering clutch.
You will generally then lose the ability to disengage that particular clutch. However, it is unlikely you could lose drive to that side, unless the disengaging piston has jammed and is holding the steering clutch disengaged.

You can find out if you have failing bevel gear bearings by removing the thin plate that covers the PTO hole on the centre of the rear upright face of the steering clutch housing, inserting a crowbar under the bevel gear shaft and prying in an up-and-down motion. There should be no movement at all in the shaft. Serious amounts of movement indicate a failed bearing - and major back end repairs.

Of course, if a winch or any PTO-driven equipment is fitted, you will need to remove that, to access the bevel gear compartment.

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6 years 5 months ago #182698 by edb
Replied by edb on topic Trans Oil Supply Tube
Hi Team,
way back when, first place we looked for Trans Safety Valve setting issue, etc. was to check the 4M8303 "O" Ring seals on the 2S5718 Sleeve connecting the Trans.oil supply from the outside rear of the trans case to the flow control valve (Early machines) inside the Trans. I cannot recall what later machines have, maybe an orifice or external Priority valve.
This gave priority to the Steering System before the trans could operate--for Safety Reasons.

The tube/sleeve has a flange on the outer end and if the Trans Modulation Valve inside the Trans case is not set just so, and the flange is not square with the case face then the "O" Rings are stressed and not supported correctly and so fail. This causes oil flow and pressure losses in the Trans/Steer systems.
There is clearance in the Trans Mod. Valve body bores for the hold down bolts. The Valve Body needs to be slightly loose so that it can be orientated so as to squarely fit/align the tube flange to the case.

Most times the bore in the receptacle area for the tube was worn by the tube at the inner "O" Ring grooves. The groove lands need to be bronzed up and bought back to standard to fully support the soft heat resisting yellow "O" Rings, also the bore of the valve (early) or body (later) needs to be bored and sleeved to reinstate that area too.

Scans below may help. To access the flanged end tube mentioned above remove the oil supply line to the trans and steer clutch control valves on the rear face of the Trans. Case and it should be able to be pulled out and the "O" Ring at the inner end inspected--most times they were worn/eroded half size in diameter section or half missing or totally missing.
Hope this helps.
Cheers,
Eddie B.
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