TB 1140 Slew Problems

[V8Druid]

I also checked the relief valves. They are set correctly. A little short of 330bar which would be correct setting. So by that I can assume there isn’t over pressurization in the hydraulic motor to create the valve plate separation from the rotor.

that is a hell of a pressure .. where are you getting the setting from ? ... that's the sort of level I'd expect an MPRV to be set to, or just slightly higher

 

[Taat]

that is a hell of a pressure .. where are you getting the setting from ? ... that's the sort of level I'd expect an MPRV to be set to, or just slightly higher

And MRV has a pressure setting of 343bar.

 

[Mick-the-fitter]

Have a ou got the motor out in bits?

 

[Taat]

Have a ou got the motor out in bits?

Not currently, i will through the weekend, but I expect that there will only be wear on the valve plate.

 

[Taat]

After disassembling I will probably take the brake valve to my workplace, check and remachine the surface connected to the hydraulic motor housing. My current guess is that the surface is curved and offsets the valve plate on the rotor.
Would that make sense?

 

[Mick-the-fitter]

After disassembling I will probably take the brake valve to my workplace, check and remachine the surface connected to the hydraulic motor housing. My current guess is that the surface is curved and offsets the valve plate on the rotor.
Would that make sense?

Yes, would make sense, also check any spring/s

 

[Taat]

Yes, would make sense, also check any spring/s

I was thinking if the springs could be at fault. There are four little disk springs pushing on the rotor. Are they notorious to lose tension and go bad?
I will order them and addition to that a new ball guide, shoe holder and swash plate. With the rotary group and bearings already replaced all the components will be new, except the shaft and the housing. I measured it one time already and is offsetting below 0.01mm, so I know the shaft is not at fault.

After that and remachining the surfaces the motor better be working like new. I better not see a drizzle of leakage after that. If not I immediately go and tear it apart again!

 

[Taat]

Here I am explaining a bit:

If anybody notices something I missed, please let me know.
I can always upload more pictures!

 

[Taat]

Pictures of important parts:

 

[Taat]

I have measured the parts.
Piston shoes haven’t lost any material, as well as cylinder block. Pistons are air tight in the bores when you plug them on the cylinder block and the shoes.
Valve plate lost about 0.05mm of material on the side with deeper scratch marks. Is that enough to cause drift and leakage?
I have also centered the brake valve according to the surface where valve plate sits and found that the surface that comes with contact with lower part of the hydraulic motor is basically flat, except around the screw holes theres a deviation of 0.05mm-0.1mm. Again I don’t know what is the tolerance on this surface and if that would cause any offset to the valve plate and its wear.
I have yet to check the housing for the lower part of hydraulic motor although I am not sure by which surface to center.

 

[Mick-the-fitter]

Where’s the rest of the motor?

 

[Taat]

Where’s the rest of the motor?

I have yet to take out the lower part of the housing and the shaft. I ran out of time yesterday…

 

[Taat]

Heres the shaft and the housing:

 

[Taat]

Heres the shaft and the housing:

If you take a look at the spline that comes with the cylinder block on that part it’s a little worn. I can also feel some more play on that section with the cylinder block than on the fresh part of the spline. Does that tell anything?

 

[Mick-the-fitter]

Have you got room to lay all the parts out on a bench in order? As long as the driven part that sits on that splined shaft is the same length as the worn part of it, then good, if it is shorter it is moving up and down the shaft slightly giving end float hence some loss of contact pressure on the valve plate!

 

[Taat]

Have you got room to lay all the parts out on a bench in order? As long as the driven part that sits on that splined shaft is the same length as the worn part of it, then good, if it is shorter it is moving up and down the shaft slightly giving end float hence some loss of contact pressure on the valve plate!

I can try to do that. Do you want me to take a picture later?
I ordered a new shaft. I am not taking a chance on anything anymore.

 

[Taat]

I can try to do that. Do you want me to take a picture later?
I ordered a new shaft. I am not taking a chance on anything anymore.

By the way I checked the bottom housing and it is in a good condition. The surface contacting to the brake valve is perfectly flat and all the bores are in 0.05mm of concentricity, which I believe is up to standard.

 

[Taat]

Have you got room to lay all the parts out on a bench in order? As long as the driven part that sits on that splined shaft is the same length as the worn part of it, then good, if it is shorter it is moving up and down the shaft slightly giving end float hence some loss of contact pressure on the valve plate!

Disk springs are missing, I don’t have them with me currently. And friction and set plates.

 

[Taat]

New disk springs arrived today. Stacked together I measured the old ones to be 0.2-0.3mm shorter compared to the new ones.
Could that be enough to cause the cylinder block to not push enough to the valve plate?

 

[Mick-the-fitter]

New disk springs arrived today. Stacked together I measured the old ones to be 0.2-0.3mm shorter compared to the new ones.
Could that be enough to cause the cylinder block to not push enough to the valve plate?

Possibly when under pressure!