RAM 1500 Truck 4WD V8-4.7L (2008)
3-4 Shift Valve After Shift
This exposes a larger passage into the piston retainer resulting in a much faster clutch fill and apply sequence. The quick fill valve does not bypass the
regular clutch feed orifice throughout the 3-4 upshift. Instead, once a predetermined pressure develops within the clutch, the valve closes the bypass.
Clutch fill is then completed through the regular feed orifice.
THROTTLE VALVE
Throttle Valve
In all gear positions, the throttle valve is being supplied with line pressure. The throttle valve meters and reduces the line pressure that now becomes
throttle pressure. The throttle valve is moved by a spring and the kickdown valve, which is mechanically connected to the throttle. The larger the throttle
opening, the higher the throttle pressure (to a maximum of line pressure). The smaller the throttle opening, the lower the throttle pressure (to a minimum
of zero at idle). As engine speed increases, the increase in pump speed increases pump output. The increase in pressure and volume must be regulated to
maintain the balance within the transmission. To do this, throttle pressure is routed to the reaction area on the right side of the throttle pressure plug (in
the regulator valve).
The higher engine speed and line pressure would open the vent too far and reduce line pressure too much. Throttle pressure, which increases with engine
speed (throttle opening), is used to oppose the movement of the pressure valve to help control the metering passage at the vent. The throttle pressure is
combined with spring pressure to reduce the force of the throttle pressure plug on the pressure valve. The larger spring at the right closes the regulator
valve passage and maintains or increases line pressure. The increased line pressure works against the reaction area of the line pressure plug and the
