B7100D Rear Implements Drift Down

[rcsroper]

My B7100D purchased new in 1974 has 2080 hours ... I notice implements won't stay put and drift down. I adjust lowering speed with the hydraulic needle valve when I change from tiller to box scraper. I suspect leakage in the control valve itself causing problem. So ... is there anything simple I can try before taking it in to a dealer?

Thanks in advance for your help.

Rick

 

[North Idaho Wolfman]

More likely the cylinder or rings are the issue.
Pull the cover and inspect.

Taking that to a dealer would be a pretty costly event.

 

[TheOldHokie]

My B7100D purchased new in 1974 has 2080 hours ... I notice implements won't stay put and drift down. I adjust lowering speed with the hydraulic needle valve when I change from tiller to box scraper. I suspect leakage in the control valve itself causing problem. So ... is there anything simple I can try before taking it in to a dealer?

Thanks in advance for your help.

Rick

Raise any implement and completely close the lowering valve. If it still leaks down its the cylinder.

Valve problems on those models is usually loss of tension in the lever itself.

Dan

 

[rcsroper]

My B7100D purchased new in 1974 has 2080 hours ... I notice implements won't stay put and drift down. I adjust lowering speed with the hydraulic needle valve when I change from tiller to box scraper. I suspect leakage in the control valve itself causing problem. So ... is there anything simple I can try before taking it in to a dealer?

Thanks in advance for your help.

Rick

More likely the cylinder or rings are the issue.
Pull the cover and inspect.

Taking that to a dealer would be a pretty costly event.

There is no hydraulic cylinder, only a hydraulic control valve shown on page 45 of the original parts manual. There is a "spool" (part #66611-3629) operated by the up down lever which must direct hydraulic pressure from the pump mounted at front of tractor. The control valve parts diagram shows an "adjusting screw" (#66591-3636) accessible from a small removable cover. It must increase/decrease spring (66591-3635) pressure, but it's not clear what affect that has on the implement hydraulics.

See attached parts diagram for "control valve group"

Raise any implement and completely close the lowering valve. If it still leaks down its the cylinder.

Valve problems on those models is usually loss of tension in the lever itself.

Dan

 

[TheOldHokie]

There is no hydraulic cylinder, only a hydraulic control valve shown on page 45 of the original parts manual. There is a "spool" (part #66611-3629) operated by the up down lever which must direct hydraulic pressure from the pump mounted at front of tractor. The control valve parts diagram shows an "adjusting screw" (#66591-3636) accessible from a small removable cover. It must increase/decrease spring (66591-3635) pressure, but it's not clear what affect that has on the implement hydraulics.

See attached parts diagram for "control valve group"

The "spool" is the valve and it operates a hydraulic cylinder.

Close the lowering control valve and see if leakdown stops.

Dan

 

[Russell King]

@rcsroper

The 3PH cylinder is inside the tractor, not an external hydraulic cylinder like on a front end loader

You can find it in the illustrated parts list that is available here

Kubota Tractor Corporation - Illustrated Parts List

- K-PAD - Parts Lists - Illustrated Parts Lists - diagrams

apps.kubotausa.com

Here is a screenshot of the parts on my L185 since the similar diagram for your tractor was less clear than these two. The blue shows the speed control apparatus that is over the cylinder that is in the yellow. The piston goes into the cylinder (but is pulled to the side for illustration purposes).

 

[North Idaho Wolfman]

There is no hydraulic cylinder, only a hydraulic control valve shown on page 45 of the original parts manual.

So you think the three point moves via magic pixie dust?

DO NOT open up the control valve and start "adjusting things" that not your problem, and no good will come of it.

The valves rarely have any issues and they rarely have any issue with the three point drooping and drifting.

The drop speed adjustment is external so no need to open it up and go searching for it, it's right out in the open.

@Russell King has the right idea but let's clear this up a bit.

This is a B7100 three point cylinder and piston and rings.

There is no drop speed control on the cover it's on the valve.

 

[torch]

I notice implements won't stay put and drift down.

Rick

Over what? Seconds, minutes, hours or days? They all drift down right from the factory, it's only a question of how fast they drift down.

For comparison, my B7100 with similar hours will take about 2 days for the 3ph to fully drop a 400lb snowblower from max lift to the ground.

 

[TheOldHokie]

Over what? Seconds, minutes, hours or days? They all drift down right from the factory, it's only a question of how fast they drift down.

For comparison, my B7100 with similar hours will take about 2 days for the 3ph to fully drop a 400lb snowblower from max lift to the ground.

I was/am surprised by the lack of leakdown on my L3901. It will seemingly hold for weeks on end. They must have done something creative....

Dan