HOSE-REDUCER 2743624 - Caterpillar

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
A resolver is a check valve. A resolver compares two pressures and the lower pressure is blocked. The higher pressure becomes the signal pressure. The signal pressure continues to the next component in the resolver network.Each control valve section in the hydraulic system has two resolver check valves. One of the check valves is called the primary resolver. The other check valve is called the secondary resolver.
Illustration 1 g00551103
Typical Control Valve (1) Secondary resolver. (2) Primary resolver.Primary resolver (2) is installed parallel to the control spool. Primary resolver (2) has a built-in ball check valve. Primary resolver (2) compares the head end pressure of the cylinder to the rod end pressure of the same cylinder.Secondary resolver (1) is installed perpendicular to primary resolver (2). The ball check valve is not in a housing. A plug holds the ball check valve in the control valve body. Secondary resolvers (1) are arranged in series, and lead to the pressure and flow compensator valve. Secondary resolver (1) in each valve section works in the same manner as primary resolver (2). Secondary resolver (1) compares the pressure signals between the valve sections.The highest resolved signal from the implement control valve goes to the pressure and flow compensator valve on the pump. This signal pressure now instructs the pump to vary the output in order to meet the highest resolved load requirements. The pressure and flow compensator valve adds margin pressure to the load requirements. Note that the signal resolver network does not add the various loads together. Instead, the single highest resolved load and the margin pressure govern pump output. The entire system is supplied with an additional 2000 kPa (290 psi) for the margin pressure which is above the amount that is necessary in order to control the single largest load. The pump will not change the output until the signal resolver network identifies a different highest resolved signal.Troubleshooting the Signal Resolver Network
The signal resolver network can be easily checked.
Start the engine. Run the engine at high idle. Operate the control levers and move all the cylinders in order to increase the temperature of the hydraulic oil to normal operating temperatures.
Illustration 2 g00584371
Left Side of Machine (3) Step assembly.
Remove step assembly (3) in order to allow access to the pressure tap on the pressure and flow compensator valve.
Illustration 3 g00584373
Piston Pump (4) Pressure tap.
Attach a 30000 kPa (4350 psi) gauge to signal pressure tap (4). Operate each control lever in the correct order.
Operate the brake through four or five applications. Next, operate the steering control. Next, operate the decking blade. Next, operate