Functional and lifetime test stands


Functional and lifetime test stands

Function and lifetime tests for components and assemblies require the specification to be checked for service life/ durability and functionality. The parameters of resilience, strength and lifecycle are decisive features in product development.

We would be happy to manufacture the required system / device for you. The test stands are designed and built in our plant engineering department.

Fatigue strength test using the example of car gearshift forks

With the shift fork test bench, the installation situation of a shift fork in a vehicle transmission is simulated and its fatigue strength behavior is determined on the basis of long-term tests.

The shift fork test stand consists of a total of four test stations, each of which can be designed for a specific shift fork type according to customer requirements.
Schaltgabelprüfstand Draufsicht
Shift fork test bench with four stations
Vier Stationen-Schaltgabelprüfstand - Draufsicht
Shift work test bench top view
The four test stations are operated in a common oil pan, with each station having a foldable splash guard made of plexiglass so that they can run under oil and the leakage oil can flow back into the tank of the hydraulic unit. The test stations stand on a frame under which the hydraulic unit is located.
Control device for shift forks

Inspection characteristics

The test series of a total of 375,000 working strokes can be divided into several cycle stages, e.g. in seven stages with 50,000 strokes and the last stage with 25,000 strokes.

Before you go to the next test stage, you need to apply "pit stops". These "pit stops" are necessary because the ball cage and the clips on the test item have to be replaced after each stage.

The sleeves in which the ball bearings run must also be checked and, if necessary, replaced.

At the end of each cycle stage (e.g. every 50,000 strokes), the respective test station switches off automatically to enable this replacement work.
The number and type of cycles can be varied individually - however, the total number of specified strokes (e.g. 375,000) is retained in each case..
Prüfvorrichtung für PKW-Schaltgabeln
Test device for car gearshift forks

After each cycle stage of 50,000 working strokes:

Replacement of ball bearings and clips, as well as quality inspection of the sleeve.

Program Sequence

Test programs
Depending on the requirements of the component, you can choose between different test programs on the operator panel.

Test program 1
A certain pressure value is determined (e.g. 20 bar) and after a certain time (e.g. 500 ms) the distance covered (waypoint) is recorded.

Check program 2
A certain force (e.g. F = 1.000 N) is specified and the program waits until the corresponding pressure is reached. Then the waypoint is recorded.

Position measurement
The stroke of the component is determined by a position measuring system. This system has to be calibrated once. The measuring range is set here to 40mm.
The reference position is the position in which the component is in the inserted, pressureless state. The zero point is set from the left on the measuring rod by spacer sleeves of different lengths.
The end points of the measuring range are determined by an external programming device which is connected to the analog outputs of the measuring unit.
Pressure sensors
The pressure sensors send an analog signal to the PLC. This is converted by using a scale and shows the actual pressure in bar on the control panel.
This pressure feedback is also required for program 2. It is queried whether the target pressure corresponds to the actual pressure.

Pressure valves
The valves are proportional valves that are controlled by the analog outputs of a PLC and by a signal amplifier.
By scaling to the operating pressure of the hydraulic pump, each pressure can be individually adjusted.

Force measurement
The measurement of the actual force acting on the workpiece can be done by a load cell, especially for each cylinder