HEAD-CYL 5S1870 - Caterpillar

Illustration 1 g00590912
Sectional View of Pilot ManifoldThe travel parking brake dual pressure control valve directs pilot oil to two circuits. One circuit supplies pilot oil to the load sensing signal relief valve in order to increase system pressure for travel. The second circuit sends pilot oil in order to release the travel parking brakes. Actuation of either travel pilot valve spool supplies pilot oil from the resolver manifold. The pilot oil shifts the position of the spool.
Illustration 2 g00590913
Travel Parking Brake Dual Pressure Control ValveShown with Brakes that are EngagedWhen travel pilot valves are not actuated no travel pilot signals are sent to the pilot manifold. The force from pilot pressure from the resolver manifold is less then the force of the spring. The spring moves the spool upward. The spool in the upper position opens the passage to the tank. Pilot oil vents to the tank drain. The spool in the upper position closes the passage for low pilot pressure. The force of the brake spring is greater than the force from pilot pressure, and the brake spring applies the travel parking brakes.When the line to the load sensing signal relief valve is vented to the tank drain, the load sensing signal relief valve regulates the main system pressure to a pressure of 31000 kPa (4500 psi) maximum.
Illustration 3 g00590915
Travel Parking Brake Dual Pressure Control ValveShown with Brakes that are DisengagedWhen the travel pilot valves are activated, travel pilot pressure is sent from the resolver manifold to the pilot manifold. The force from pilot pressure from the resolver manifold is greater than the force of the spring. The force from pilot pressure moves the spool downward. The spool in the lower position opens the passage for low pilot pressure. The low pilot pressure is sent through the passage to the load sensing signal relief valve and travel parking brakes. Some of this oil goes to the ladder position solenoid valve. When the travel pilot valve is actuated, an electrical signal is sent to the machine control module. If the ladders are in the stowed position, an electrical signal is sent from the machine control module which energizes the ladder position solenoid valve. When the ladder position solenoid valve is energized, pilot oil is allowed to flow to the travel parking brakes and the load sensing signal relief valve. The force from pilot pressure releases the travel parking brakes. The spool in the lower position closes the tank drain passage. The pilot oil signals the load sensing signal relief valve in order to regulate the main system pressure to a maximum pressure of 35000 kPa (5075 psi).