hydraulic systems and apply devices
DESCRIPTION
HYDRAULIC SYSTEMS and APPLY DEVICES. Chapter 5 Page 106 Control Devices. 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. Page 106. VALVE TYPES. CHECK VALVES Ball valves - PowerPoint PPT PresentationTRANSCRIPT
HYDRAULIC SYSTEMS and APPLY DEVICES
Chapter 5 Page 106 Control Devices
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.
Page 106
VALVE TYPES
CHECK VALVES
Ball valves Poppet valves Needle valves
REGULATION VALVES
Relief valves Orifices Spool valves
Page 106
CHECK VALVES
One way valve To stop back flow Directional control valve
– Figure 5-14 page 107
RELIEF VALVES
A check valve fitted with a spring will not open until hydraulic pressure becomes greater than spring force.
Figure 5-16
Page 108
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. Page 108
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. Page 109
CONTROL VALVES
A flow directing fluid to different outlet ports.
Page 110
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.
Page 110
VALVE BODIES
Page 110
PRESSURES 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 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 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
Action of vane-type pump:
Maximum output– page 106
Pressure Regulator
Valve Action of
vane-type pump:
Minimum output– page 106
PRESSURE REGULATOR
GOVERNORS Spool
valve type
Check ball type
Page 115
VEHICLE SPEED SENSOR
There are three types of speed sensors.– Magnetic pulse generator - most common– Hall effect switch– Optical sensor
Page 117
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
Page 117
VACUUM MODULATOR
Uses engine vacuum to sense engine load and adjust line pressure and shift points.
Page 117
THROTTLE LINKAGES
Page 118
Uses a cable or linkage to sense engine load and adjust line pressure and shift points.
THROTTLE LINKAGES
Adjust throttle linkage before TV linkage
Page 118
MAP SENSOR
Manifold Absolute Pressure Sensor MAP sensor generates a voltage in direct
relation to engine load. 0 to 5 volts
Page 120
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.
Page 120
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..
Page 120
MANUAL VALVE
The manual valve is a spool valve manually operated by the gear selector linkage.
Page 120
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.
Page 120
ELECTRONIC SHIFT-TIMING CONTROLS
Sensor inputs Actuator outputs
Page 121
SOLENOID VALVES
Most solenoid-operated valves are ball-type valves that open and close a hydraulic passage.
Page 121
OIL CIRCUITS
Trace one circuit at a time. Start at the oil pump.
Page 121