Test Stand for Synchromesh Gearboxes


To test gearbox components and complete gearboxes at different ambient temperatures and determine torque, shifting force, input and output speed.

To test the relative movement of the synchronizer rings while shifting a pair of gears (1st and 2nd gears). To apply predetermined braking torques ba means of a loading unit.

To measure the input and output speeds as well as the differential speed, shifting force, selector fork friction moment, synchronising torque, synchronizer ring movement and gear lever movement while shifting gears and evaluate the measured data by means of a computer.

To simulate the real-life force applied by the coasting vehicle by installing a flywheel behind the electric motor.


The task was solved by fabricating a tilting base and equipping it with a clamping plate provided with slots for mounting an angle plate to which the gearboxes to be tested can be secured with bolts.

The test stand essentially consists of:

  • Tilting base with clamping plate for a test box or compete gearbox
  • Driveline with torque measuring point and flywheel
  • Oil supply unit
  • Gear shifting unit with separate hydraulic fluid supply
  • Ambient air heating and cooling unit
  • Insulated test chamber
  • Test box
  • Loading unit for test box
  • Means of calibrating torque measuring shaft in driveline
  • Drive motor
  • Switchgear cabinet for power pack
  • 19″ cabinet for measuring and control modules
  • Control panel
  • Computer for measured data acquisition

Control panel

The control panel is installed in the 19″ cabinet.

Computer for measured data acquisition

A computer is used for measured data acquisition and evalation.
A printer provides hard copy printouts. An interface card transfers the digital values to the computer.
The software provided for the stored-program control system affords a high degree of operator convenience in manual operation.
In the automatic mode, control is assumed by the computer. The scanning rate during measurements is 500 Hz.

Description of the individual components:

Test stand base with clamping plate for mounting a test box or complete gearbox. The test stand base is supported on a rugged tubular frame and tilts max. 5� to one side.
The clamping plate for the test box is provided with T-slots and suitable sealing lips around the circumference for the cooling box.
Design and accuracy of the clamping plate conform to the applicable DIN standards.
The entire surface of the top of the test stand base is machined to Grade 3, DIN 876.
The main drive motor is installed in the base of the test stand and operates at 3,000 rpm, providing a maximum input shaft speed of approx. 5,000 rpm.

Test stand base with clamping plate for mounting a test box or complete gearbox

The driveline is mounted on an adjusting plate in the centre of the test stand, permitting accurate adjustment in all three axes.
The flywheel is installed between two bearings and adequately balanced and stabilized for high speeds.
The input shaft is dynamically balanced (Grade G 2.5 to VDI Specification 2060).

Oil supply unit

The oil supply unit supplies the gearbox with oil heated or cooled to the desired temperature.

The hydraulic unit permits operating temperatures between 20 and 150°C.
The maximum system pressure is 10 bar. The heating system permits the use of oil with different viscosities.

The complete oil supply unit designed for operation at extreme temperatures and with different types of oil.

The time required for heating-up to a temperature of 159°C is approx. 60 minutes.
Safe control is assured by a temperature limiting device with unlocking button in accordance with VDE specifications for 0°C to 250°C. The complete oil supply unit is mounted on wheels.

All oil circuit and hydraulic components meet the most exacting requirements of hydraulic engineering.
Movements are controlled hydraulially and monitored by means of two force and position transducers.
The measuring amplifiers and control modules for the gear shifting unit are housed in the 19″ cabinet.
The gear shifting unit is equipped with RS 232 serial interfaces for connection to the stored-Program control system, connection to the computer and for programming the system via manual input.