Part 2
System Description ContinuedHydraulic Control
The hydraulic control system is controlled by the ATF pump, the valves, and the solenoids. The ATF pump is driven by the input shaft. The ATF pump and the input shaft are linked by the ATF pump drive chain and the sprockets. Fluid from the ATF pump flows through the PH regulator valve to maintain specified pressure to the drive pulley, the driven pulley, and the manual valve.
The lower valve body assembly includes the main valve body, the secondary valve body, the CVT driven pulley pressure control valve, the CVT start clutch pressure control valve, and the CVT drive pulley pressure control valve.
The manual valve body is bolted on the intermediate housing, and houses the manual valve which switches hydraulic pressure to meet with the shift lever position.
Main Valve Body
The main valve body contains the start clutch shift valve, the shift inhibitor valve, the lubrication regulator valve, and the cooler relief valve.
^ Start Clutch Shift Valve
When a control system malfunction occurs, the start clutch shift valve receives shift inhibitor pressure (SI) and covers the port of lubrication pressure bypass circuit.
^ Shift Inhibitor Valve
The shift inhibitor valve switches the fluid passage to switch the start clutch control from electronic control to hydraulic control when the electronic control system is faulty.
^ Lubrication Regulator Valve
The lubrication regulator valve stabilizes the lubrication pressure to the internal circuit.
^ Cooler Relief Valve
The cooler relief valve stabilizes the ATF cooler pressure and recirculation pressure to the ATF cooler and to the internal circuit.
Secondary Valve Body
The secondary valve body contains the pressure high (PH) regulator valve, the pressure high control (PHC) shift valve, the start clutch back-up valve, the clutch reducing valve, and the start clutch accumulator.
^ PH Regulator Valve
The PH regulator valve maintains hydraulic pressure supplied from the ATF pump, and supplies PH pressure to the hydraulic control circuit and the lubrication circuit. PH pressure is regulated at the PH regulator valve by the PH control pressure (PHC) from PHC shift valve.
^ PHC Shift Valve
The PHC shift valve supplies PH control pressure (PHC) to the PH regulator valve to regulate PH pressure in accordance with the drive pulley control pressure (DRC) or driven pulley pressure (DNC).
^ Start Clutch Back-up Valve
When a control system malfunction occurs, the start clutch back-up valve supplies start clutch control B pressure (CCB) based on shift inhibitor pressure (SI) to the start clutch.
^ Clutch Reducing Valve
The clutch reducing valve receives PH pressure from the PH regulator valve and regulates clutch reducing pressure (CR).
^ Start Clutch Accumulator
The start clutch accumulator stabilizes the hydraulic pressure that is supplied to the start clutch.
CVT Driven Pulley Pressure Control Valve
The CVT driven pulley pressure control valve contains the driven pulley control valve with the solenoid and pulley control valve A. The driven pulley control valve controls the position of pulley control valve A to applying driven pulley pressure (DN) to the driven pulley.
CVT Drive Pulley Pressure Control Valve
The CVT drive pulley pressure control valve contains drive pulley control valve with the solenoid and pulley control valve B. The drive pulley control valve controls the position of pulley control valve B which applies drive pulley pressure (DR) to the drive pulley. The combination of the CVT driven pulley pressure control valve and the, CVT drive pulley pressure control valve applying pulley control pressures to the respective pulleys provides complete power transfer, eliminating steel belt slippage and increasing belt life.
CVT Start Clutch Pressure Control Valve
The CVT start clutch pressure control valve consists of the start clutch pressure control valve and the solenoid. The CVT start clutch pressure control valve controls start clutch engagement according to the throttle opening.
Manual Valve Body
The manual valve body contains the manual valve and the reverse inhibitor valve. The manual valve body is bolted on the intermediate housing.
^ Manual Valve
The manual valve mechanically uncovers/covers the fluid passage according to the shift lever position.
^ Reverse Inhibitor Valve
The reverse inhibitor valve is controlled by reverse inhibitor (RI) pressure from the reverse inhibitor solenoid. The reverse inhibitor valve intercepts the hydraulic pressure flowing to the reverse brake while the vehicle is moving forward at speeds over about 6 mph (10 km/h).
Hydraulic Flow
As the engine turns, the ATF pump starts to operate. CVT fluid (CVTF) is drawn through the ATF strainer and discharge into the hydraulic circuit. Then, CVTF flowing from the ATF pump flows the PH regulator valve and becomes pressure high (PH) pressure. PH pressure flows to the pulley control valves and then to the pulleys.
The PCM actuates the solenoids to control hydraulic pressure shifting pulley ratio and engaging the start clutch.
Hydraulic pressure at the port is as follows
N Position
Fluid from the ATF pump is regulated to high pressure at the PH regulator valve, and flows to the pulley control valves. The CVT driven pulley pressure control valve and the CVT drive pulley pressure control valve control pulley control valves A and B to apply pressure to the pulleys. The driven pulley receives pressure higher than the pressure drive pulley receives, but hydraulic pressure to the forward clutch is intercepted by the manual valve and to the start clutch is intercepted by the CVT start clutch pressure control valve. Under this condition, hydraulic pressure is not applied to the start and forward clutches.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position, at low speed range
The manual valve is shifted into the D position, and uncovers the port leading forward clutch pressure (FWD) to the forward clutch. The forward clutch pressure (FWD) flows to the forward clutch, the forward clutch is engaged, and drives the input shaft and drive pulley shaft. The drive pulley receives low pressure, and driven pulley receives high pressure. The PCM actuates the CVT start clutch pressure control valve to control start clutch pressure. The start clutch control pressure (CC) from the CVT start clutch pressure control valve becomes the start clutch pressure (SC) at the shift inhibitor valve, and flows to the start clutch. The start clutch is engaged, and the vehicle moves.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position, at top speed range
As the speed of the vehicle reaches the programmed value, the PCM controls the CVT driven pulley pressure control valve and the CVT drive pulley pressure control valve to provide about the same hydraulic pressure to the pulleys. The diameter in contact with the steel belt on the drive and driven pulleys becomes nearly equal, and the pulley ratio is in high. Hydraulic pressure is then applied to the start and forward clutches.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position, at high speed range
Vehicle speed is further increased, the PCM controls the CVT driven pulley pressure control valve and the CVT drive pulley pressure control valve to apply hydraulic pressure to the drive pulley and to the driven pulley. The drive pulley receives high pressure and the driven pulley receives low. The drive pulley provides the steel belt a large-diameter contact and the driven pulley provides a small-diameter contact, and the result is a high pulley ratio. Hydraulic pressure remains to apply to the start and forward clutches.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
R Position
The manual valve is shifted into the R position, uncovers the port leading to the reverse brake pressure (RVS) to the reverse inhibitor valve. The reverse inhibitor solenoid is turned OFF by the PCM, and reverse inhibitor pressure (RI) is applied to the right end of the reverse inhibitor valve. The reverse inhibitor valve is moved to the left side, and uncovers the port leading reverse brake pressure (RVS) to the reverse brake. Clutch reducing pressure (CR) becomes reverse brake pressure (RVS), and flows to the reverse brake via the reverse inhibitor valve. The reverse brake is engaged, and it locks the planetary carrier.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
R Position: Reverse Inhibitor Control
If the R position is selected while the vehicle is moving forward at speeds over 6 mph (10 km/h), the PCM outputs signal to turn ON the reverse inhibitor solenoid, and reverse inhibitor pressure (RI) in the right end of the reverse inhibitor valve is released. The reverse inhibitor valve is moved to the right side, and uncovers the port to stop reverse brake pressure to the reverse brake from the manual valve. Reverse brake pressure (RVS) is not applied to the reverse brake, and power is not transmitted to the reverse direction.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
P Position
The manual valve is shifted into the P position, the manual valve intercepts hydraulic pressure to the forward clutch. Hydraulic pressure is not applied to the start and forward clutches, and power is not transmitted to the drive pulley shaft.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
D Position, when an electronic control system malfunction occurs.
When an electronic control system malfunction occurs in the D position, the CVT start clutch pressure control valve cannot operate the control start clutch pressure circuit, the transmission creates a temporary circuit for the start clutch pressure control to allow the vehicle to be driven.
The CVT start clutch control valve covers the port leading start clutch control pressure (CC) to the shift inhibitor valve, and the shift inhibitor valve is moved to the left side by drive pulley control pressure (DRC). Clutch reducing pressure (CR) becomes shift inhibitor pressure (SI) at the shift inhibitor valve, flows to the left side of the start clutch back-up valve, and becomes start clutch,control B pressure (CCB). Start clutch control B pressure (CCB) becomes start clutch pressure (SC) at the shift inhibitor valve, and flows to the start clutch. Clutch reducing pressure (CR) also flows to the manual valve and becomes forward clutch pressure (FWD). The start clutch and the forward clutch are engaged, and the vehicle will move.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
R Position, when an electronic control system malfunction occurs.
When an electronic control system malfunction occurs in the R position, and the CVT start clutch pressure control valve cannot operate the control start clutch pressure circuit, the transmission creates the temporary circuit of the start clutch pressure control to allow the vehicle to be driven.
The CVT start clutch control valve covers the port leading start clutch control pressure (CC) to the shift inhibitor valve, and the shift inhibitor valve is moved to the left side by drive pulley control pressure (DRC). Clutch reducing pressure (CR) becomes shift inhibitor pressure (SI) at the shift inhibitor valve, flows to the left side of the start clutch back-up valve, and becomes start clutch control B pressure (CCB). Start clutch control B pressure (CCB) becomes start clutch pressure (SC) at the shift inhibitor valve, and flows to the start clutch. Clutch reducing pressure (CR) also flows to the manual valve and becomes reverse brake pressure (RVS). The start clutch and the reverse brake are engaged, and the vehicle will reverse.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.
Park Mechanism
The park mechanism locks the transmission by engaging the park pawl with the park gear which is integral with the secondary drive gear. The secondary drive gear engages with the secondary driven gear which is splined to the final drive shaft, and the final drive gear integrated with the final drive shaft engages the final driven gear.
Shifting to the P position causes the park cone (installed at the end of the park rod) to press the park pawl onto the park gear. Even if the end of the park pawl rides on the top of the park gear teeth, slight movement of the vehicle will cause the park pawl and park gear to mesh with each other completely because the park rod spring puts tension on the park cone. The park pawl receives the tension (which acts to separate the park pawl from the park gear) from the park pawl spring.
