I have a cat 428c series 8rn single tilt on the bucket.The…

Did you change the seals in the inlet section of the loader valve?

Did you remove and clean the steering priority valve in the inlet section?

How does the rest of the backhoe functions work?

Can you stall a backhoe function and see the power return to the loader controls?

Sorry for the late reply, this question was missing from my list. I had to track it down to find your posting.

Is it possible you have trash in the hydraulic system?

This appears to be a signal leak from a resolver. Did a resolver ball get left out?

Have you check the filter for debris in the hydraulic oil?

Did the machine has a recent failure? Any signs of other repairs like new hoses or repaired cylinders?

Here are details about the resolvers.

There are two resolvers per implement control valve. Primary resolver compares the rod end hydraulic pressure to the hydraulic pressure for the head end of the cylinder. Secondary resolver compares the highest primary signal in the control valve to the highest primary signal in the next control valve. The secondary resolvers are arranged in series and the secondary resolvers lead to the pump compensator valve.

A resolver is a shuttle valve that is a double ball check valve. The resolver compares the two pressures. The highest pressure moves the ball. The ball blocks the lower pressure. This higher signal pressure flows to the next resolver in the resolver network.

The primary resolvers and the secondary resolvers can be affected by the following items.

• debris

   

• cut seal

   

• missing seal

   

• bad ball resolver seat

   

• missing resolver ball

The signal network can be easily checked. Install one 6V-4143 Coupler Assembly to each end of the 6V-3014 Hose Assembly. Install the 8T-0860 Gauge with a range of 0 to 40000 kPa (0 to 5800 psi). Install 6V-3014 Hose Assembly to signal pressure tap.

Start the engine and warm up the hydraulic oil to the operating temperature. Run the engine at LOW IDLE. Operate each control lever in the following order for the 416C, 426C or 436C machines:

 

1. Auxiliary (if equipped)

 

1. Boom

 

1. Swing

 

1. Right side stabilizer

 

1. Left side stabilizer

 

1. Backhoe bucket

 

1. Stick

 

1. Extendable stick (if equipped)

 

1. Auxiliary for the loader (if equipped)

 

1. Loader bucket tilt

 

1. Lift control for the loader

 

1. Priority valve

Operate each control lever in the following order for the 428C or the 438C machines:

 

1. Boom

 

1. Swing

 

1. Left side stabilizer

 

1. Right side stabilizer

 

1. Backhoe bucket

 

1. Stick

 

1. Extendable stick (if equipped)

 

1. Auxiliary for the loader (if equipped)

 

1. Loader bucket tilt

 

1. Lift control for the loader

 

1. Priority valve

Operate each of the implements against a load. Watch the gauge. The maximum system pressure of 20700 ± 700 kPa (3000 ± 100 psi) should be reached for most of the circuits. The exceptions are the boom LOWER, the steering circuit and the loader DUMP for parallel lift machines. By using the gauge, small leakage problems such as a cut seal or a missing seal can be detected.

Secondary Resolvers with Two or More Valve Sections

If two or more of the control valves in series fail to work properly, the problem may be in the secondary resolver of an upstream implement control valve. The first control valve receives the pump supply oil first. If the secondary resolver for the control valve does not work properly, the secondary resolver may allow signal pressure from any control valve that is further from the pump supply to leak back to the tank.

This leakage may be caused by a resolver ball that is not seating or by a resolver ball that is blocking the signal oil to the drain. Signal oil from a downstream control valve may be at a higher pressure than a control valve that is closer to the pump. However, the faulty resolver will not allow the downstream valve to function properly.

A leakage in the resolver may be caused by a missing resolver ball, debris that prevents the resolver ball from properly seating, a missing seal or a leaking seal. When multiple control valves malfunction, first operate the malfunctioning valve that is farthest from the pump. Operate the other control valves, while you operate the control valve that is farthest from the pump. Operate the other control valves one at a time until a control valve operates both implements.

This is the control valve with the bad secondary resolver. The farthest control valve is sending a signal and the control valve with the faulty secondary resolver is also sending a signal. Because the control valve with the bad secondary resolver has a leak, the signal from the farthest control valve cannot flow to the pump controller until the control valve with the faulty resolver is operated.

Primary Resolver Versus Secondary Resolver

For control valves with a flow control spool, if one control valve section fails to work in one or both directions, the primary resolver or the secondary resolver in that control valve may be faulty. For control valves with a flow control spool, if one of the control valves works slowly in one or both directions, the primary resolver or the secondary resolver in that control valve may be faulty. In order to determine the faulty resolver, perform the following check.

Stall an implement control valve downstream from the malfunctioning valve. This will force the malfunctioning valve's secondary resolver ball to move away from the seat on the drain end.

This eliminates the possibility of a leak on the drain end of this secondary resolver. While you stall the downstream control valve, operate the malfunctioning control valve. If the control valve is still operating slowly in one or both directions, then the primary resolver may be faulty.

When the primary resolver is faulty, the faulty resolver bleeds off the pressure, which affects the operation of the flow control spool. The combined force of the signal oil pressure and the flow control spring is not enough to move the spool. This prevents additional oil to flow to the cylinder. The load on the cylinder is greater than the amount of oil that is flowing to the cylinder, which causes the implement to have a slower response.

Normally if an implement is slow in both directions, the problem is usually in the secondary resolver. If an implement is slow in only one direction, the cause is typically caused by a faulty primary resolver.

The causes for a faulty primary resolver are the same causes for a secondary resolver. A leakage in the resolver may be caused by a missing resolver ball, debris that prevents the resolver ball from properly seating, a missing seal or a leaking seal.

Other causes of a malfunctioning valve section might be a misadjusted linkage, a broken pressure reducing valve spring, a flow control spool that is incorrectly installed, a faulty line relief valve or a faulty makeup valve.

Note: As a recommendation, flush the system if there is debris in the system. Flush the system by removing all of the resolver balls in the secondary resolvers. Then operate the implements. There will be enough oil flow in order to flush the debris to the tank.

Follow this test and let me know the results. Hopefully this will point you to the faulty resolver.

Hello, I will be glad to help you with this.

Please start a new question and include the machine, transmission and torque divider/convertor serial numbers. These machines have been rebuilt for so long some changes may be present that are not identified under just the serial number prefix.

Thank you, Donnie

Can you zoom in on the images I sent you?

When I click on the planetary image, it will zoom in and is very clear.

All contact is limited to this site per policy.

If you cannot upload the image through the upload / edit functions on the toolbar here, use a cloud or online drive or a picture account and send me a link just like the link I sent you.

I used OneDrive and posted the image in my public folder. Then you can create a share link and post is here.

I also use Dropbox and have seen others use Flicker. Just look for the online storage option and then share to create a link to the image.

It usually works better than the upload edit function on this site.

I must leave for work now so, my reply my be later in the day.

I will try to respond during a break if I can get online.