190303e Flashcards
Identify four (4) of the major hydraulic retarder components
a) retarder rotor (rotating assembly)
b) retarder housing (stator)
c) oil pump and oil supply circuit
d) oil cooler (heat exchanger)
e) retarder control valve and control circuit
Explain the purpose of the hydraulic retarder rotor.
The retarder rotor is the rotating member of the hydraulic retarder. It is attached to a
powertrain member output. As the rotor vanes strike the oil in the retarder housing,
resistance occurs. That drag is transmitted to the driveline, thereby slowing the
vehicle.
Explain the purpose of the retarder/stator housing.
The retarder housing encloses the retarder rotor and contains the oil supplied during
retarder operation. The close clearance between the rotor and the housing causes the
rotor to drag as it passes through the oil. This drag slows the vehicle. A great deal of
heat occurs due to this reaction.
Explain the purpose of the oil cooler used in the hydraulic retarder system.
The cooler helps maintain the oil temperature within safe limits.
The only type of oil cooler used in the hydraulic retarder system is the oil-to-air
design.
t/f
false;
Identify the three (3) possible locations where hydraulic retarders could be
positioned.
a) between the torque converter and transmission
b) on the transmission output shaft
c) on the driveline
Explain the basic operation of a hydraulic retarder.
The operator moves a mode selector switch or lever in order to activate the hydraulic
retarder.
The hydraulic retarder changes the heat energy created by the vehicle moving over
the road into kinetic energy.
a) true
b) false
false;
The hydraulic retarder operates on the basis of a change in fluid friction.
a) true
b) false
true
What is the stationary member in a retarder?
Retarder/stator housing
The position of the hand air valve controls the amount of air pressure applied. An increase in air pressure to the retarder hydraulic valve causes
A higher pressure of oil inside the retarder, due to centrifugal force of oil thrown out by the rotor, increasing braking force
When a retarder is installed between engine and torque converter what is required?
A lockup clutch inside torque converter
When retarder is applied the lockup clutch engages putting the torque converter in what state?
Direct drive
What force over comes the spring pressure in the retarder control valve
Air pressure
What force counter acts the air pressure in the retarder control valve?
Oil pressure plus spring pressure
When hydraulic retarder troubleshooting, after an external inspection, what must also be done?
Pull the magnetic drain plug and filter element. Look for shiny steel particles, aluminum particles, rubber particles or iron and steel chips
What are the possible different sources of oil for a hydraulic retarder
It’s own tank, engine, transmission and or the torque converter
The retarder is most efficient when it is connected directly to what?
The driveshaft.
In a powershift transmission what is the best way to connect a retarder to the driveshaft?
With a lock up clutch
The biggest concern in any hydraulic retarder is what?
The heat rise. Electronic controlled hydraulic retarder’s have many inputs and outputs to run the retarder as efficiently as possible, and to warn of high temp
A hydraulic retarder works on the ____ instead of the wheels.
Driveline
In addition to the service brakes, the optional hydraulic retarder provides assistance with ____ the machine.
Slowing
True or False
The oil pump that supplies oil to the torque converter and transmission may also be used to supply oil to the hydraulic retarder?
True
Separate oil pump, reservoirs, oil coolers, and oil supply or return circuits may be used when retarder’s are mounted where?
Transmission output shaft or on the driveline
True or False
Oil-to-coolant type oil coolers are the only
Oil coolers used with torque converter/retarder oil circuits?
False
What are three methods of controlling a retarder?
Manual operator control
Air over hydraulic control
Electronic control
Where is an input hydraulic retarded located in relation to the transmission?
In front of the transmission.
Output hydraulic retarded are located on the output of the engine. (T/F)
False
A hydraulic retarded maybe used ad a supplementary park brake. (T/F)
False.
