FRAME GP 2723243 - Caterpillar

Illustration 6 g00939161
Swing control valve during a right hand swing (2) Directional control valve (3) Swing dual pressure relief valve (4) Left swing motor (5) Flow to drain (6) Manifold section (7) Makeup check valve (9) Makeup check valve (10) Right swing motor (12) High pressure load spool and poppet (13) Dump valve (14) Shuttle spool for the relief valve (15) Low pressure load spool and poppet (17) Pilot signal oil (right swing) (18) Load check valve (19) Makeup check valve (20) Positive flow control pressure oil to the swing piston pump (21) Makeup check valve (22) Load check valve (23) Orifice and check valve (24) Resolver valve (25) Circuit oil flow (26) Check valve (27) Swing control spool (28) Pilot signal oil (left swing) (30) Port (right swing motor) (31) Ports to the left swing motor and to the dual pressure relief valvePump discharge oil (29) through directional control valve (2) is blocked at the left chamber and the center chamber by control valve spool (27). The two adjacent chambers on the right are connected because control valve spool (27) has shifted left. Circuit oil flow (25) goes to right swing motor (10) through the right side port (30). Circuit oil flow (25) goes to manifold section (6) of swing control valve (1) through port (31) .In Section B-B, circuit oil flow (25) leaves directional control valve (2) through port (31), and flows through manifold section (6) to swing dual pressure relief valve (3). Circuit oil flow (25) closes the makeup check valve (9) and flows to left swing motor (4) .In Section E-E, load check valve (22) at the top right is opened by circuit oil flow (25). Circuit oil flow (25) enters the wishbone shaped chamber to dump valve (13) through the small orifice into the small internal passage to swing dual pressure relief valve (3). Circuit oil flow (25) passes around the shuttle spool for the relief valve (14) and through the orificed passage into the end of high pressure load spool and poppet (12) and into the end of low pressure load spool and poppet (15). Circuit oil flow (24) pushes both load spools to the left, which compresses both relief valve springs.In Section C-C, circuit oil flow (25) is entering the relief valve center internal passage. The circuit oil flow (25) then goes around the shuttle spool for the relief valve (14) to the high pressure load spool and poppet (12). Circuit oil flow (25) is blocked by the top land on the shuttle spool for the relief valve (14). Circuit oil flow (25) cannot go to the low pressure load spool and poppet (15). High pressure relief load spool and poppet (12) remains seated until the swing circuit pressure reaches 35000 kPa (5080 psi). When pump discharge pressure reaches 35000 kPa (5080 psi), the poppet moves off the seat against the force of the high pressure relief valve spring. Circuit oil will pass through the poppet to drain (5). The resulting pressure