Page 35 of 40
3
Referring to the chart below. The “x” axis (the bottom line) represents the
coefficient of friction; 1 is very low: 10 is very high. Look along this line from left
to right. Pick a vertical line that is approximately the value of the coefficient of
friction. Look vertically upward along this line. It crosses a series of angled
lines, these lines are numbered U1, U2 etc. where the vertical line crosses the
angled line with the U figure determined from step 1 make a mark on the chart.
Draw a horizontal line (parallel with the other horizontal lines on the chart) from
the marked point. Where this line crosses the “y” axis (the vertical line at the
extreme left hand of the chart), make a second mark on the chart. The height
of this line represents the % of maximum clockwise rotation of the torque
control. If this line is very close to the figure 0.5 marked on the “y” axis, set the
torque control potentiometer approximately one half of the way around its
maximum travel etc.
There is an alternative way of arriving at the appropriate setting for the torque control
potentiometer. Do the following.
Select a sample of the cable to be used. Pass the cable through the machine as
described in the manual. Feed the cable into the beginning of a length of sample tube
(say 5 metres long). Seal the open end of the tube. Position the torque control
potentiometer at the position determined by the recommendations in this Appendix,
Start the machine. Drive the cable hard into the sealed end of the sample length of
tube. The rollers will stop turning, this is because the torque limit has been reached.
Repeat this procedure, each time turning the torque potentiometer a little further
clockwise. Eventually, the cable will buckle. The setting of the torque control
potentiometer is now a little too far clockwise. Turn it back (counter clockwise) a little.
This is the optimum setting.
Torque potentiometer setting
0
0.25
0.5
0.75
1
1
10
Coeff of friction
%
o
f
m
a
x
im
u
m
r
o
ta
ti
o
n
(
c
lo
c
k
w
is
e
)
U1
U2
U3
U4
U5
U6
