Valvebody Basics

1
Valvebody Basics
2
Transmission Hydraulic Pressures

• Mainline Pressure
• Throttle Pressure
• Governor Pressure

3
Pressure Regulation

• Regulator Valve
• Variable Regulated Pressure

Building to Max Pressure
4
Pressure Regulator Valve

• Bleeds off pressure when maximum pressure is
  reached.
• Exhausts back to sump
• If left unregulated can damage components

5
Mainline Pressure(line pressure)

• Regulated Mainline Pressure is source for all
  flow
• Controlled by pressure regulator
• Applies bands and clutches
• Feeds Valve Body valves
• Applies pressure to one end of pressure regulator
  valve

6
BOOST PRESSURE

• Boosted Mainline Pressure
• Boost Valve to raise pressure at low rpm and high
  engine load
• Other pressures are used to modify regulated
  pressure

7
Throttle Pressure(modulated pressure)

• Engine Load Sensing
• Mechanical
• Vacuum
• Works against governor pressure
• Primary Shift Control signal
• Always less or equal to mainline pressure

8
Mechanical Throttle Valve Operation
9
Throttle Valve OperationLow Pressure
10
TV Valve PressureHigher Pressure
11
Vacuum Operated Throttle Valve(vacuum modulated)
Page 68c
12
Governor Pressure

• Governor Types
• Gear Driven
• Spool Valve Type
• Check-ball Type
• Shaft Mounted
• Valves allow fluid to not bleed off the higher
  speed you go.
• Governors stick sometimes and can be cleaned

• Road Speed signal
• Opposes TV pressure to control shift points
• Driven by output shaft
• Higher speeds Higher pressure

13
Centrifugal Governor Operation
Spool Valve operated
14
Shaft Mounted Governor
15
Check ball style Governor
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Shifting and Shift Operations

• Manual Valve
• Throttle Valve
• Downshift Valves
• Governor Valve
• Spool Valve design
• Check-ball design
• Shaft Mounted governors

17
Manual Valve Operation

• Positioned manually by gear selector lever
• Lever moves valve to one of several detent
  positions
• Directs mainline pressure to correct shift valves
  and apply devices

18
Shift Valve Operation

• Shift Valves are
• Flow directing
• Switching valves
• Spool Type valves
• Governor Pressure on one end
• Throttle Pressure on other end with spring assist
• Blocks or allows fluid flow
• Valves must move instantly

19
Shift Valve Operation
-When speed is high, governor pressure is higher
than throttle pressure. -Allows mainline pressure
to pass through and cause a upshift
When Vehicle speed low Throttle pressure and
spring Pressure are higher than Governor
pressure
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Valve Body(The Brain)
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Hydraulic CircuitLow Gear

• 1 2 Shift valve controls upshifts and
  downshifts between
• first and second gears
• 2 3 shift valve controls upshifts and
  downshifts between second and third gears

22
Hydraulic CircuitSecond Gear
23
Hydraulic CircuitThird Gear