3B Scientific Friction Measuring Apparatus - Manual (Page 2)

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3. Technical data
Friction track
U-shaped track:
600 x 80 x 20 mm 3
Protractor: 0° – 60°
Sliding friction surface
Material:
PVC, smooth on one
side and coarse on the
other side
Length: 850 mm
Friction body A
Dimensions:
79 x 38 x 73 mm 3
Material: PVC
Surface: Uncoated
Surface area ratio: 2:1
Weight: 325 g approx.
Fastening rings: 2
Friction body B
Dimensions:
73 x 20 x 47 mm 3
Material: PVC
Surface: Coated with velour pa-
per
Weight: 100 g approx.
Additional weights
Design:
To fit friction body B
Weight: 100 g
Sliders
Design:
To fit friction body B
Material: Aluminium
Surface: Rubber-coated (No. 1),
Teflon-coated (No. 2),
Uncoated (No. 3)
Dimensions: 55 x 55 x 15 mm 3
Friction body C
Dimensions:
75 x 31 x105 mm 3
Surface: Coated with velour pa-
per
Weight: 325 g
Securing rings: 2
Castors: 2, ball-bearings
Dynamometer
Measuring range:
2 N, tension and com-
pression
4. Set-up
• Secure the dynamometer by means of the
clamp.
• Attach a stopper for the friction body to the
U-shaped track (the stopper prevents any
sudden recoil of the friction body that might
arise as the sliding friction surface is pushed
back.)
5. Measurements conducted on a horizontal
friction plane
• Align the friction track so that the pointer on
the protractor is in the zero position.
• Insert the sliding friction surface into the
friction track either with its smooth or coarse
facing down. Then place a friction body onto
the sliding friction surface. (See Fig. 1 and
Fig. 2.)
5.1 Static friction
• Pull the sliding friction surface, making sure
it is displaced with a uniform motion.
• Read the maximum value from the dyna-
mometer while the friction body is still being
dragged along with the sliding friction sur-
face.
• Perform this measurement on several occa-
sions and calculate the average.
This value represents a measure of the static
frictional force.
5.2 Sliding friction
• Conduct measurements as described under
5.1. However, take the reading on the dy-
namometer as soon as the friction body has
stopped moving along with the sliding fric-
tion surface.
• Perform this measurement on several occa-
sions and calculate the average.
This value represents a measure of the sliding
frictional force.
Fig. 1: Investigation of static and sliding friction with
friction body A with two different contact areas.