527 Track-Type Skidder Hydraulic System Caterpillar

Each control valve section in the implement hydraulic system has two resolver check valves. Each resolver check valve compares two pressure signals. The higher signal of the two signals goes to the next resolver. One of the check valves is called the primary resolver. The other check valve is called the secondary resolver.

Illustration 1	g00451972
Typical Control Valve (1) Primary resolver (2) Secondary resolver

The primary resolver is installed parallel to the control spool. The ball check valve is built into the resolver. The secondary resolver is installed perpendicular to the primary resolver. The ball check valve is not contained in a housing. A plug holds the ball check valve in the valve body.

Illustration 2	g00451973
Primary Resolver (3) Signal line from the cylinder head end (4) Outlet line (5) Ball check valve (6) Signal line from the rod end

Outlet line (4) feeds the resolved signal to the secondary resolver and the spring end of the flow control.

The primary resolver compares the pressure between the two work ports in each control valve section.

In the previous illustration, the head end pressure in line (3) is greater than the rod end pressure in line (6). The head end pressure forces ball check valve (5) to the left. This blocks line (6). The pressure in line (3) is the highest resolved pressure in this resolver. This pressure travels through outlet line (4) to the next resolver.