190303E Flashcards
What type of braking system is a hydraulic retarder?
It is a supplementary or auxiliary braking system
Can a hydraulic retarder stop a machine?
No it can only help to slow down the vehicle or piece of equipment
Where are three locations a hydraulic retarder can be located?
At the end put between the transmission and the torque converter.
At the output of the transmission.
And in a remote location or driveline
What are some basic components of a hydraulic retarder?
Rotor, housing (stator), oil pump, oil cooler, control valve, wet brake and an accumulator
What type of vanes can a rotor have?
Straight or angled
What is the purpose of the retarder housing?
It encloses the retarder rotor providing a place for oil
Where does the hydraulic retarder get its oil from?
The same oil circuit as the torque converter and transmission or another source
At what temperature does oil burn off additives?
121 degrees Celsius or 250 degrees Fahrenheit
What is another type of oil cooler other than oil to coolant type?
Oil to air cooler
Retarder’s are controlled by three methods they are?
Manual operator control, air over hydraulic controls, electronic control
What switches and sensors are involved in an automatic control valve and circuit?
Ignition switch, mode selection switch or lever, clutch position switch and transmission and gear indicator, a fuel control position indicator (throttle position sensor)
If the ignition is off can the hydraulic retarder activate?
No it cannot
True or false. Are all hydraulic retarders modulated?
Some are not modulated they are either on or off
If a hydraulic retarder can be modulated by the operator. Is it done manually, pneumatically or either?
It can be modulated manually or pneumatically.
When is a wet brake system activated?
While the hydraulic retarder is Filling with oil. It is released once the hydraulic retarder is operational.
Why are hydraulic accumulator is used more on hwy or trucking applications?
Because in Offroad equipment we have a larger hydraulic pumps
Does a air accumulator have springs?
No it does not
How is an air accumulator triggered?
With a solenoid
How much oil is left in the retarder housing when the retarder is not in use?
Just enough to lubricate moving parts.
Can a hydraulic retarder be used in conjunction with an engine or exhaust brake?
Yes all three can be used at the same time
Out of the three auxiliary braking systems, which is activated first?
The engine or exhaust break will be activated first. On long downhill grades the hydraulic retarder will be activated
What is the energy conversion in a hydraulic retarder?
Kinetic energy by moving the vehicle is turned into heat energy from turbulence in the oil
When does the rotor turn freely?
When the vehicle or piece of equipment is moving
Is friction inside the hydraulic retarder higher or lower when oil is added?
The more oil added the more friction is created, slowing the output down
What can happen if the retarder oil temperature rises higher than 135°C?
If the temperature rises above 135°C it can cause damage to the retarder. To avoid this you must apply the service brake or put the transmission in a lower speed
What is required on a torque converter if the retarder is mounted in between the crankshaft flange and the flywheel?
The torque converter must have a lock up clutch
How much torque is the torque converter multiplying when the retarder is activated?
The torque converter should not be multiplying torque
When is the retarder most efficient?
When it is connected directly to the driveshaft
When is a synchronizing valves used with a retarder?
When there is two transmissions on a piece of equipment. The synchronizing valve will prevent engagement of one transmission until the other transmission is in the right relation
What happens when a hydraulic retarder is too small for its application?
It will create too much heat and deteriorate the oil quality.
In what type of working condition should you increase oil change intervals?
When the equipment is working in mountainous terrain’s and carrying heavy loads
The powertrain ECM needs what inputs?
Throttle position sensor,retarder oil temperature sensor, output shaft speed sensor, retarder enabled device, break application pressure sensor
Which outputs are controlled by the powertrain ECM?
Retarder control valve solenoid? Warning light, brake lights, over temperature light
What tools can help you troubleshoot and diagnose hydraulic retarder electrical faults?
A scan tool, Digital multimeter, a fault code light system
Why should you check the magnetic plug or filter elements?
If you find different metals on the magnet or in the filter it can help you troubleshoot the retarder
What could be the problem if you find shiny steel particles on the magnetic plug?
Possibly a pump failure or the pump is wearing
What could be a problem if you find aluminum particles inside the filter element?
It could be the retarder rotor wearing
What could be a problem if you find rubber particles inside the filter element?
You could have a seal or hose failure
If you find iron or steel chips on the magnetic plug or inside the filter elements what could be the problem?
There are broken components
