303E: Hydraulic Retarder Fundamentals

Question 1

Identify the major hydraulic retarder components. (7)

Answer 1

• Retarder rotor (rotating assembly)
• Retarder housing (stator-stationary)
• Oil pump and oil supply circuit
• Oil cooler (heat exchanger)
• Retarder control valve and control circuit
• Wet brake system
• Accumulator

303E Pg. 5

Question 2

Explain the purpose of the hydraulic retarder rotor.

Answer 2

• Rotating member
• Generally attached to the torque converter or transmission output shafts or driveline
• Rotates within the Retarder/Stator housing to shear/churn the oil

303E Pg. 6

Question 3

Explain the purpose of the retarder/stator housing.

Answer 3

• Stationary member
• Encircles and encloses the retarder rotor
• Holds the oil

303E Pg. 7

Question 4

The only type of oil cooler used in the hydraulic retarder system is the oil-to-air design. (T/F)

Answer 4

False

Oil-Coolant
Oil-Air

303E Pg. 8

Question 5

Identify the three possible locations where hydraulic retarders could be positioned.

Answer 5

Input Retarder: Between the torque converter and transmission
Output Retarder: Transmission output shaft
Remote Mount: Driveline

303E Pg. 2

Question 6

Explain the basic operation of a hydraulic retarder.

Answer 6

Oil is sheared between the rotating rotor and stationary stator housing. The churning of oil generates heat, converting the kinetic energy to heat energy, which is then cooled by the cooler.

303E Pg. 12

Question 7

The hydraulic retarder operates on the basis of a change in fluid friction. (T/F)

Answer 7

True

303E

Question 8

What is the stationary member in a hydraulic retarder?

Answer 8

Retarder/stator housing

303E Pg. 7

Question 9

When a hydraulic retarder is installed between the engine and torque converter, what component is also required for proper operation?

Answer 9

• A lockup clutch inside the torque converter
• When engaged, direct drive from engine through torque converter to transmission

303E Pg. 20

Question 10

In what mounting location is a hydraulic retarder most efficient?

Answer 10

The driveshaft

303E Pg. 22

Question 11

In a powershift transmission what is the best way to connect a hydrulic retarder to the driveshaft?

Answer 11

Lockup clutch with the use of a synchronizing valve.

303E Pg. 22

Question 12

What are three methods of controlling a hydraulic retarder?

Answer 12

• Manual operated
• Air over hydraulic
• Electronic

303E Pg. 9

Question 13

Where would an Input hydraulic retarder be mounted?

Answer 13

Integral part of the transmission assembly. Between torque converter and transmission.

Downshifting transmission greatly increases retarder effectiveness

303E Pg. 2

Question 14

Where would an Output hydraulic retarder be mounted?

Answer 14

Transmission output shaft

Braking force exerted directly on driveline independant of engine rpm

303E Pg. 3

Question 15

Where would a remote mounted hydraulic retarder be mounted?

Answer 15

Driveline

Most efficient mounting location

303E Pg. 3

Question 16

With what mounting location, is a multi-disc clutch used with hydraulic retarders to quickly begin the retarding process?

Answer 16

Output Mounted: Transmission output shaft

303E Pg. 4