SUPPORT 1761914 - Caterpillar

Manual Modulation Valve
The manual modulation valve lets the operator control the P2 pressure to the directional clutches and move the machine a little distance at a time. The left foot pedal in the operator's compartment is connected to the manual modulation valve with a cable.
Hydraulic Controls In Third Speed With Manual Modulation Valve Closed
(1) Passage. (2) Chamber. (3) Orifice. (4) Piston. (5) Slug. (6) Spool. (7) Passage from load piston. (8) Load piston. (9) Modulating reducing valve.When the left foot pedal is up and the manual modulation valve is not being used, spool (6) is in the position shown. P1 pressure from the load piston (8) goes through passage (7) and is stopped by the spool (6). P2 pressure goes around piston (4) and to the direction clutches. P2 pressure also goes through orifice (3) and into chamber (2) where the pressure is stopped. P1 and P2 are at their maximum pressures.When the left foot pedal is pushed down, spool (6) is moved out as shown. Passage (7) from the load piston is connected to passage (1) which lets P1 pressure oil from the load piston (8) go to the reservoir. The location of the orifice for passage (7) at the load piston (8) prevents P1 pressure from going lower than 620 kPa (90 psi). The clutches are now operating at a lower pressure.At the same time that passage (7) is connected to passage (1), chamber (2) is also connected to passage (1) which lets P2 pressure oil in the chamber go to the reservoir. P2 pressure on the slug (5) moves the piston (4) to the left and causes a restriction to the P2 oil flow around the piston (4). This restriction causes a decrease in pressure of the P2 oil to the direction clutches.P2 pressure can be controlled from approximately 69 to 1000 kPa (10 to 145 psi) by the manual modulation valve. Because the direction clutches are not fully engaged, the operator can slip the clutch (make the discs slide in relation to the plates) and move the machine a little distance at a time.When the operator lets the pedal come back up, spool (6) moves back in and the P1 and P2 pressures increase to their maximum pressures. The modulating reducing valve (9) gives modulation to the pressure oil and lets the clutches engage smoothly.
Hydraulic Controls In Third Speed With Manual Modulation Valve Opened
(1) Passage. (2) Chamber. (3) Orifice. (4) Piston. (5) Slug. (6) Spool. (7) Passage from load piston. (8) Load piston. (9) Modulating reducing valve.Differential And Bevel Gear
Differential (On Machines With a Differential)
The differential is used to send power from the transmission, through the final drives, to the wheels. When the rear wheels on one side are turning slower than the rear wheels on the other side (as in a turn) the differential lets the inside wheels stop or turn slower in relation to the outside wheels.The output flange of the transmission turns the shaft for bevel gear pinion (6). Bevel pinion