Siemens Milltronics MCS Instruction Manual page 12

Head Pulley
Use caution when installing a scale in a short conveyor or when locating the scale near
the head pulley. Since head pulleys are flat-faced and carrying idlers are generally
troughed, the belt profile must change from troughed to flat in a short distance. To
accommodate this, the conveyor manufacturer designs a built-in vertical displacement of
the head pulley above the top of the center roll of the adjacent idler. To further ease this
transition, idlers of decreasing trough angles are inserted between the head pulley and
the normal run of idlers. If these measures are not taken, a considerable amount of stress
is exerted on the belt edges and the idlers adjacent to the head pulley. In turn, this stress
is transmitted to the scale causing an unreliable measurement.
Recommendation:
scale idler a minimum of two fixed 20° idlers away from the head pulley
.
20° idlers
Recommendation:
scale a minimum of two 35° and one 20° retreat idler away from the head pulley.
35° idlers
Page 8
On conveyors with 20° trough idlers throughout, install the
belt scale
On conveyors with 35° trough idlers throughout, install the
belt scale
MCS Belt Scale – INSTRUCTION MANUAL
minimum 3 idler spaces
minimum 4 idler spaces
35° idlers
head pulley
20°
idler
head
pulley
7ML19985HN61