1. HYDRAULIC SYSTEMS and APPLY DEVICES
Chapter 5
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Control Devices

2. CONTROL DEVICES
The oil pump is the source of all fluid flow through the Trans.
The valve body regulates and directs fluid flow to provide gear changes.
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3. VALVE TYPES CHECK VALVES Ball valves Poppet valves Needle valves
REGULATION VALVES
Relief valves
Orifices
Spool valves
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4. CHECK VALVES One way valve To stop back flow Directional control valve
Figure 5-14 page 107

5. RELIEF VALVES
A check valve fitted with a spring will not open until hydraulic pressure becomes greater than spring force.
Figure 5-16
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6. ORIFICES
Orifices are used in transmissions to control dynamic pressures.
A number of orifices are often placed in series to provide a cushioning effect on the hydraulic system.
Orifices are used for gradual activation of an apply device, which improves shift quality.
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7. SPOOL VALVES
Spool valves are the most commonly used valve in a transmission.
Spools are precisely machined to fit into a bore and are connected by the valves stem.
The stem has a smaller diameter than the spools.
The stem is not a precisely machined part of the valve.
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8. CONTROL VALVES A flow directing fluid to different outlet ports.
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9. RELAY VALVES
A relay valve is a spool valve with several spools, lands, and reaction areas.
It is used to control direction of flow.
Does not control pressure.
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10. VALVE BODIES
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11. PRESSURES
All automatics use 3 basic pressures to control their operation:
Mainline Pressure - Pressure Regulator valve
Throttle Pressure - Throttle valve
Governor Pressure - Governor Valve
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12. BOOST PRESSURES Line pressure is a regulated pump pressure.
Increasing pressure increases holding power of bands & clutches.
Throttle pressure is applied to a booster valve at the PR.
Some transmissions use two boost valves.
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13. PRESSURE REGULATOR VALVE
Pressure will increase with engine speed.
PR valves use the principles of both pressure relief and a spool valve.
Some PR valves use 3 types of boost - TV, Manual 1, Reverse.
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14. Pressure Regulator Valve
Action of vane-type pump:
Maximum output
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15. Pressure Regulator Valve
Action of vane-type pump:
Minimum output
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16. PRESSURE REGULATOR

17. GOVERNORS
Spool valve type
Check ball type
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18. VEHICLE SPEED SENSOR There are three types of speed sensors.
Magnetic pulse generator - most common
Hall effect switch
Optical sensor
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19. LOAD SENSOR
Shift timing and quality should vary with engine load, as well as vehicle speed.
There are three ways to do this:
Vacuum modulator
TV cable or linkage
Map sensor and computer
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20. VACUUM MODULATOR
Uses engine vacuum to sense engine load and adjust line pressure and shift points.
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21. THROTTLE LINKAGES
Uses a cable or linkage to sense engine load and adjust line pressure and shift points.
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22. THROTTLE LINKAGES
Adjust throttle linkage before TV linkage
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23. MAP SENSOR Manifold Absolute Pressure Sensor
MAP sensor generates a voltage in direct relation to engine load.
0 to 5 volts
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24. SHIFT TIMING
Shift timing is determined by throttle position and governor pressure acting on opposite ends of the shift valve.
When accelerating at a steady rate governor pressure will overcome a steady throttle pressure and cause the shift valve to stroke up-shifting the transmission.
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25. SHIFT VALVES Shift valves are spool valves.
Movement of the shift valve is controlled by:
A spring holding the valve in the down-shift position.
Changing throttle pressure holding the shift valve in the down-shift position.
Governor pressure increasing with road speed forcing the shift valve to the upshift position..
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26. MANUAL VALVE
The manual valve is a spool valve manually operated by the gear selector linkage.
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27. KICKDOWN VALVE
Vacuum, electrical, or linkage signals are sent to the valve body causing a sudden increase in throttle pressure.
Actual downshift is controlled in many ways.
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28. ELECTRONIC SHIFT-TIMING CONTROLS
Sensor inputs
Actuator outputs
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29. SOLENOID VALVES
Most solenoid-operated valves are ball-type valves that open and close a hydraulic passage.
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30. OIL CIRCUITS Trace one circuit at a time. Start at the oil pump.
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