LEVER AS 2787218 - Caterpillar

Illustration 1 g01776273
(1) RH Stabilizer Control Valve (2) LH Stabilizer Control Valve (3) Inlet (4) Resolver (5) Load signal Relief valve (6) Resolver (7) Stick Control Valve (8) Extendable Stick Control Valve (9) Pump (10) Relief Valve (11) Spool (12) Inlet (13) Lift Control Valve (14) Spool (15) Line (16) Auxiliary Control Valve (17) Resolver (18) Line (19) Valve (20) Spring (21) Resolver (22) Spring (23) Resolver (24) Resolver (25) ResolverA resolver compares two pressure signals. The resolvers in the backhoe loaders are connected in series within the hydraulic system. The resolver compares the pressure between the active circuits in the hydraulic system. The higher pressure signal goes to the next resolver.The resolver is installed perpendicular to the control spool. A ball check valve is built into the resolver. The ball check valve is not contained in a housing. A plug holds the ball check valve in the valve body. The network for the resolvers begins at the backhoe control valve. Hydraulic oil flows from inlet (3) in the backhoe control valve to inlet (12) on the loader control bank valve. When the loader controls and the backhoe controls are in the Neutral position, no oil flows to the resolver network. The signal oil drains through the spool in each control valve to the tank.In the implement hydraulic system, the stabilizer valve (1), the extendable stick control valve (8), and the auxiliary control valve for the loader (16) do not contain resolvers. All other implement control valves contain one resolver. The priority valve in inlet (12) has only one resolver. This is resolver (23) .The loader control bank valve will be used in order to explain the operation of the resolver network.When the operator actuates lift control valve (13), hydraulic oil flows into inlet (12) to spool (11). Spool (11) is the priority valve spool. The spool keeps the steering system filled with oil. When the oil pressure overcomes the force of spring (22), the spool moves to the left. Hydraulic oil flows to both the steering system and the loader control valves.When the hydraulic oil flows across spool (14) for the lift circuit, some of the hydraulic oil flows through line (15) to valve (19). When the oil pressure overcomes the force of spring (20), the hydraulic oil moves the valve to the left. Oil flows through the valve. Then, the line splits into two branches. One line goes to resolver (21). This oil becomes the load signal oil. The other line goes back to the spool for the lift circuit. The hydraulic oil flows through the spool to the activated circuit.The oil flows to resolver (21). If the lift circuit is the only branch of the loader system that is active, or if the lift circuit has the highest pressure in the loader system, the ball check valve will move to the left. The load signal oil will flow to resolver (23). The ball check valve in resolver (23) will move to the left. The load signal