COUPLING- 2710662 - Caterpillar

Illustration 1 g01388991
Typical metering pump (1) Centering springs (2) Outlet to tank (3) Internal check valve (4) Inlet port (5) Passage (6) Passage from gerotor (7) Drive shaft (8) Spool (9) Pin (10) Passage to the left turn port (11) Passage to the right turn port (12) Sleeve (13) Passage to gerotor (14) Gerotor (A) Control section (B) Metering sectionThe steering wheel is connected to the metering pump by a mechanical linkage.The two sections (A) and (B) are connected by hydraulics and by mechanics. The two sections work together in order to provide oil to the steering cylinder. Pump oil goes through inlet (9) into control section (A). When the steering wheel is turned, control section (A) sends oil to metering section (B). Metering section (B) produces a specific amount of oil flow. Metered oil from metering section (B) is then directed by control section (A) to either the passage to the left turn port (10) or the passage to the right turn port (11) .Metering section (B) is a small hydraulic motor. The hydraulic motor produces a metered amount of oil flow. Then, the metered oil is directed by the control section (A) to the steering cylinder. The direction and the speed are controlled by the metering pump. As the steering wheel is turned faster, there is an increase in the flow of oil from the steering metering pump to the cylinder. The increased flow causes the cylinder to move faster. This turns the machine faster.When the steering wheel is not being turned, control section (A) is in the NEUTRAL position. The metering pump is a closed center valve. This means that there is no alignment between the passages in the spool and the orifices in the sleeve in the NEUTRAL position. Only a small amount of oil flows through the center position. This keeps the spool slightly open and ready to respond quickly to any steering demands.When the steering wheel is turned for a right turn, pump oil flows into the metering pump through inlet (4) and passage (5). From passage (5), oil flows into gerotor (14) through passage (13). While the steering wheel is turned, gerotor (14) turns. The gerotor also pumps oil while the steering wheel is turned. The oil flows outward through passage (6). This oil is directed to the steering cylinder through the right turn port.
Illustration 2 g01388998
Spool and sleeve (8) Spool (9) Pin (12) Sleeve (15) Slots for springs (16) Grooves for oil flow (17) Holes for pin (18) Small holes for oil flowWhen the steering wheel started to turn, spool (8), pin (9), and drive shaft (7) also started to turn. The sleeve (12) did not start to turn at the same time as the spool. The holes in the sleeve (17) are slightly larger than the pin (9). The difference allows the spool to turn inside the sleeve. This aligns the small holes in the sleeve (18) with the grooves in the spool (16). The alignment of the holes and of