Friction is a key factor in mechanical engineering. Static friction needs to be adequate to fix components to each other, such as parking brakes, self-locking threads and frictionally engaged connections. Dynamic friction needs to be kept as low as possible, such as on bearings, in guideways or in shaping tools. Consequently, great attention is paid to the topic in engineering mechanics, and understanding of it is enhanced by clearly laid-out experiments.
The unit provides a broad range of experiments relating to static and dynamic friction between solid bodies which are in contact with each other and moving relative to each other. Various influences on friction can be investigated, such as surface properties and material pairing.
A support friction surface slides beneath the stationary friction body. The support friction surface is held in a carriage which is drawn along by a motor at uniform speed by a motor. The friction body is connected to a height-adjustable force measuring unit. This ensures that the lines of action of friction force and tensile force are parallel. The force measuring unit is essentially a force gauge which is fitted with an air damper to compensate as far as possible for slip/stick effects and so indicate a mean friction force (with no spiking).
Three support surfaces and two friction bodies are available. The normal force can be varied by adding loads.
Experiments can be performed at two constant speeds. The air damping is adjustable. When it is inactive, slip/stick effects can also be observed.
All parts are clearly laid out and well protected on a storage system.
The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.
Learning Objectives / Experiments
- difference between static and dynamic friction
- friction forces as a function of
* normal force
* sliding speed (relative speeds of the friction partners)
* material pairing
* surface properties of the friction partners
* size of the contact area
- slip/stick effect
- determination of friction coefficients
 mechanical friction between 2 solid bodies
 friction body stationary, support friction surface in a moving carriage
 2 friction bodies each with 2 different surfaces
 3 support friction surfaces with a total of 4 different surfaces
 carriage driven by cable pulley and motor
 2 driving speeds via a graduated cable drum
 force measuring unit: force gauge and adjustable air damper
 force measuring unit height-adjustable
 lines of action of friction force and tensile force always parallel
 adjustable air damper - with damping: measurement of a mean friction force adjusted by disturbances, without damping: slip/stick effects measurable
 storage system to house all parts
Support friction surface
- LxWxH: approx. 175x80x6mm
- PVC / felt
- LxW: approx. 50x40mm
- dead-weight force: approx. 1N
- smooth / rough (Al), h=20mm
- brass / felt, h=5mm
- synchronous motor
- rotation speed: 100min-1
- driving speeds: 23,5cm/min, 47cm/min
Force gauge with damper
- measuring range: 0...2N, graduations: 0,05N
Load: 8x 0,5N
Dimensions and Weight
LxWxH: 720x480x178mm (storage system)
Weight: approx. 10kg (storage system)
Weight: approx. 7kg (experimental unit)
Required for Operation
230V, 50/60Hz, 1 phase or 120V, 60Hz/CSA, 1 phase
Scope of Delivery
1 experimental unit
1 set of loads
2 friction bodies
3 support surfaces
1 storage system with foam inlay
1 set of instructional material