PLATE 5I5200 - Caterpillar

Normal Mode
Illustration 1 g01268053
Priority Valve (NORMAL MODE)
(1) Spool Assembly
(2) Slug Chamber
(3) Spool Chamber
(4) Slug
(5) Poppet
(6) Orifice
(7) Solenoid
(8) Solenoid Spool
(9) Filter Base and Priority Valve Housing
(10) Chamber
(11) Check Valve
(12) Passage from Transmission Charging Section "C"
(13) Adjustment Screw
(14) Spring
(15) Passage to Drain
(16) Passage to Torque Converter and Torque Converter Relief Valve
(17) Passage from Torque Converter Charging Section "B"
(18) Passage to Brake Valve and Transmission Hydraulic Control
(19) Transmission Charge Filter
(20) Priority Valve
(21) Torque Converter Charge Filter
(22) Pressure Tap (Priority Valve)
(BB) Cutaway Section
(CC) Component Surface
(FF) Activated Components
(GG) Tank Pressure
(JJ) High Pressure
(KK) First Pressure Reduction
(PP) Torque Converter Pressure In NORMAL MODE, solenoid (7) is energized by the power train ECM. Oil from the torque converter charging section enters through passage (17). Oil flows through the solenoid into slug chamber (2) through orifice (6) and poppet (5).Oil from passage (17) flows around spool assembly (1) to chamber (10). When solenoid (7) is energized, oil in chamber (10) is allowed to flow through solenoid spool (8) to spool chamber (3). The pressure in spool chamber (3) acts against slug (4). This causes spool assembly (1) to shift to the right. This allows oil from the torque converter charging section to flow through passage (17) to passage (16) to the torque converter and the torque converter inlet relief valve.The pressure of the oil in chamber (10) is not higher than the pressure in passage (12). As a result, check valve (11) does not open. The oil from the torque converter charging section does not supplement the oil from the transmission charging section in passage (12).Priority Mode
Illustration 2 g01215855
Priority Valve (PRIORITY MODE)
(1) Spool Assembly
(2) Slug Chamber
(3) Spool Chamber
(4) Slug
(5) Poppet
(6) Orifice
(7) Solenoid
(8) Solenoid Spool
(9) Filter Base and Priority Valve Housing
(10) Chamber
(11) Check Valve
(12) Passage from Transmission Charging Section "C"
(13) Adjustment Screw
(14) Spring
(15) Passage to Drain
(16) Passage to Torque Converter and Torque Converter Relief Valve
(17) Passage from Torque Converter Charging Section "B"
(18) Passage to Brake Valve and Transmission Hydraulic Control
(19) Transmission Charge Filter
(20) Priority Valve
(21) Torque Converter Charge Filter
(22) Pressure Tap (Priority Valve)
(BB) Cutaway Section
(CC) Component Surface
(FF) Activated Components
(GG) Tank Pressure
(JJ) High Pressure
(QQ) Reduced Torque Converter Pressure In PRIORITY MODE, oil is supplied to the brake valve and the transmission before oil is supplied to the torque converter.The priority valve shifts to PRIORITY MODE in the following situations:
Engine speed is below 1300 rpm and the parking brake is off.
Power train oil is cold.
A transmission shift is in progress.
Transmission fill calibration is in progress.In PRIORITY MODE, solenoid (7) is de-energized. Oil from the torque converter charging section enters the priority valve through passage (17). Oil flows through orifice (6), through poppet (5), and into slug chamber (2).Oil flows from the torque converter charging section through passage (17), around spool assembly (1), and into chamber (10). Because solenoid (7) is de-energized, this oil is prevented from flowing through solenoid spool (8) to spool chamber (3). The oil in spool chamber (3) is directed to the hydraulic oil tank through solenoid spool (8).As a result, spring (14) forces spool assembly (1) to the