HYDRAULIC SYSTEMS and APPLY DEVICES Chapter 5 Page 106 Control Devices
HYDRAULIC SYSTEMS and APPLY DEVICES n Chapter 5 n Page 106 n Control Devices.
Dec 18, 2015
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HYDRAULIC SYSTEMS and APPLY DEVICES
HYDRAULIC SYSTEMS and APPLY DEVICES
Chapter 5 Page 106 Control Devices
CONTROL DEVICESCONTROL 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.
Page 106
VALVE TYPESVALVE TYPES
CHECK VALVES
Ball valves Poppet valves Needle valves
REGULATION VALVES
Relief valves Orifices Spool valves
Page 106
CHECK VALVESCHECK VALVES
One way valve To stop back flow Directional control valve
– Figure 5-14 page 107
RELIEF VALVESRELIEF VALVES
A check valve fitted with a spring will not open until hydraulic pressure becomes greater than spring force.
Figure 5-16
Page 108
ORIFICESORIFICES
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. Page 108
SPOOL VALVESSPOOL 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. Page 109
CONTROL VALVESCONTROL VALVES
A flow directing fluid to different outlet ports.
Page 110
RELAY VALVESRELAY 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.
Page 110
VALVE BODIESVALVE BODIES
Page 110
PRESSURESPRESSURES
All automatics use 3 basic pressures to control their operation:
Mainline Pressure - Pressure Regulator valve
Throttle Pressure - Throttle valve Governor Pressure - Governor Valve
Page 110
BOOST PRESSURESBOOST 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.Page 113
PRESSURE REGULATOR VALVE
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.
Page 113
Pressure Regulator
Valve
Pressure Regulator
Valve
Action of vane-type pump:
Maximum output– page 106
Pressure Regulator
Valve
Pressure Regulator
Valve
Action of vane-type pump:
Minimum output– page 106
PRESSURE REGULATORPRESSURE REGULATOR
GOVERNORSGOVERNORS
Spool valve type
Check ball type
Page 115
VEHICLE SPEED SENSORVEHICLE SPEED SENSOR
There are three types of speed sensors.– Magnetic pulse generator - most common– Hall effect switch– Optical sensor
Page 117
LOAD SENSORLOAD 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
Page 117
VACUUM MODULATOR
VACUUM MODULATOR
Uses engine vacuum to sense engine load and adjust line pressure and shift points.
Page 117
THROTTLE LINKAGESTHROTTLE LINKAGES
Page 118
Uses a cable or linkage to sense engine load and adjust line pressure and shift points.
THROTTLE LINKAGESTHROTTLE LINKAGES
Adjust throttle linkage before TV linkage
Page 118
MAP SENSORMAP SENSOR
Manifold Absolute Pressure Sensor MAP sensor generates a voltage in direct
relation to engine load. 0 to 5 volts
Page 120
SHIFT TIMINGSHIFT 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.
Page 120
SHIFT VALVESSHIFT 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..
Page 120
MANUAL VALVEMANUAL VALVE
The manual valve is a spool valve manually operated by the gear selector linkage.
Page 120
KICKDOWN VALVEKICKDOWN 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.
Page 120
ELECTRONIC SHIFT-TIMING CONTROLS
ELECTRONIC SHIFT-TIMING CONTROLS
Sensor inputs Actuator outputs
Page 121
SOLENOID VALVESSOLENOID VALVES
Most solenoid-operated valves are ball-type valves that open and close a hydraulic passage.
Page 121
OIL CIRCUITSOIL CIRCUITS
Trace one circuit at a time. Start at the oil pump.
Page 121
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