General Description:

The TE 74 Two Roller Machine is for the study of traction, wear and rolling contact fatigue under conditions of heavily loaded, lubricated, pure rolling and rolling and sliding. The machine incorporates two motors, one to provide the input power and one to absorb the transmitted power.

To achieve the necessary high loads with small diameter rollers, hence high contact pressures, the test rollers our mounted on shafts with bearings on either side, in the “fully supported” configuration. As a consequence, spindle bearings are exposed to, and must run in, the test lubricant.

To achieve satisfactory performance in line contact, the mounting/loading arrangement has adjustable alignment, with the upper specimen shaft carried on a pivoted arm and with a spherical bearing incorporated in the pivot axle. Axial alignment is achieved by indexing the pivot axle. Loading is achieved by means of a servo controlled pneumatic bellows actuator with force transducer feedback.

The lower specimen shaft is carried in fixed bearings. The drive to the lower roller incorporates an in-line torque transducer for measuring the input torque to the system. It should be noted that the traction measurement is thus subject to parasitic losses associated with the roller spindle bearings. These losses are small but may be quantified by running the unit under conditions of zero slip at different speeds and temperatures.

A vibration sensor is provided for detecting surface failure. The upper roller housing is electrically insulated and slip rings are provided on the roller shafts for electrical contact resistance measurement.

A lubricant service module is fitted as standard incorporating a sump tank with immersion heater, delivery pump, scavenge pump and oil to water heat exchangers for cooling.

The motors are a.c. and powered by conventional vector drives allowing precise control of speed. Power is re-circulated electrically via a common d.c. link between the drives, upstream of the frequency inverter stages. Total power requirement is thus limited to the system losses. For control purposes, one drive is designated as master with the second drive deriving its speed set point, adjusted for the required slip ratio, from the master drive.