TE 54 MINI TRACTION MACHINE

Description

The TE 54 Mini Traction Machine brings together proven design elements from the long

established TE 55 Two Roller Lubricity Test Machine and a scaled-down version of the common

DC link AC vector drive system used on the TE 74 Two Roller Machines. The servo pneumatic

loading system is taken straight from the TE 67 Pin on Disc/Reciprocating Pin on Plate Machine.

Why Ball on Ring and not Ball on Disc?

Traction coefficient is substantially influenced by spin and shear within the contact and, unless

one is specifically interested in these phenomena, a design that potentially introduces spin or

skew, as is the case with the ball on disc configuration, is a great nuisance. It requires a very

complicated process of adjustment of the position of the ball on the disc in order to eliminate

unwanted spin and skew

In order to eliminate spin the axis of the ball shaft must intersect precisely with the point of

intersection between the surface of the disc and the axis of the disc.

Adjustments are typically made by running the contact on either side of the zero slide/roll

condition with the intention of detecting the zero traction condition. However, this is

scientifically indeterminate, because a contact with zero slide/roll but spin will not give zero

traction.

A nominal zero may perhaps be presumed with this method, but once done, it is then not

possible to determine the exact track diameter on either the ball or the disc, thus introducing

further uncertainty.

In addition to this, to avoid skew, the ball shaft must lie precisely along a radius of the disc. To

achieve zero skew, the ball shaft position must be adjusted to bring the ball onto the radius

line. But of course, doing this once again alters the track radius on the disc.

The ball on disc arrangement is thus complex, expensive and ultimately indeterminate. By

comparison, the ball on ring arrangement automatically eliminates any possibility of spin or

skew; it eliminates any uncertainty with regard ball or track diameter; with circumferential

grinding, it eliminates all the an-isotropic materials properties associated with preparing disc

specimens.

Self-aligning Two Roller

In addition to the ball on disc arrangement, the TE 54 is also supplied with a self-aligning

carrier to allow a 25 mm diameter by 8 mm wide roller to be mounted in place of the ball

specimen, thus resulting in an 8 mm wide line contact. Thinner rollers can be manufactured in

order to produce narrower line contacts.

TE 54 MINI TRACTION MACHINE

Technical Specification

Ball Specimen Diameter: 25 mmUpper Disc Specimen Diameter: 25 mmUpper Disc Specimen Width: 8 mmLower Disc Specimen Diameter: 50 mmMaximum Ball Speed: 4,000 rpmMaximum Ring Speed: 2,000 rpmMaximum Surface Speed: 5.24 m/sMaximum Load: 500 NMaximum Hertz Pressure (steel): 2.0 GPaOil Bath Temperature: ambient to 150°CHeater Power: 250 WTemperature Sensor: k-type thermocoupleLoading System: Pneumatic bellows with force feedbackAC Vector Drive: Two 0.75 kW closed loop with common DC linkMotors: Continuous: 0.75 kW @ 50 Hz @ 1,450 rpmFeedback: 2,048 ppr encoderDrive Ratios: Motor:Ball: 1:1Motor:Ring: 2:1Interface: Serial Link Interface ModuleSoftware: COMPEND 2000

Controlled Parameters Motor speed

Motor speed differenceApplied loadTest bath temperature

Measured Parameters: Motor speed

Motor speed differenceApplied loadTraction forceTest bath temperature

Derived Parameters Entrainment Velocity

Sliding VelocitySlide/Roll RatioTraction Coefficient

ServicesElectricity: 380/415 V, three phase, 50/60 Hz, 1.5 kW, with neutral & earth

220/240 V, three phase, 50/60 Hz, 1.5 kW, with neutral & earthClean, dry air: 4 cfm at 8 bar (120 psi)