Maintenance & Tips

Pulley & V-Belt Installation & Tensioning Instructions

June 28, 2023

Rear Mounted Piston Pumps

  1. Degrease and score the gearbox and pump shafts with emery cloth before installing bushings and pulleys. This will prevent them from moving during normal operation. Used pulleys should also be cleaned and scored.
  2. On the 24” turbine machines, position the bushing on the gearbox input shaft so that 2 ½” of splined shaft is left in front. On the 30” turbine machines the position must be measured as well. A measurement can be made from the back edge of the bushing to the gearbox housing (do not measure to the rubber seal). On machines made before 06/1994 this measurement is 5/8”. Units purchased after this date use ½”. Install bushing with 5/16” x 5/16” x ¾” key stock.
  3. Install the pulley on the bushing. Torque the ¼” x 1 3/8” bolts to 9ft-lbs.
  4. Check the run-out on the gearbox pulley. Measure the run-out with a dial gauge against the inner v-groove surfaces. The outer edges of the pulley are not always machined and this makes it difficult to get a true reading. The maximum allowable run-out is 0.005”. Use the bushing bolts to adjust the run-out. The closer this pulley is to zero run-out the easier the alignment of both pulleys will be.
  5. Install the pulley on the pump shaft. Ensure that the brass 0.005” shim stock is in place around the busing before installing the pulley. Position the pulley with a straight edge so that it is 3/8” offset from the other pulley before tightening the bolts. As the bushing bolts are tightened the pulley on the pump shaft will move and line up. On 30” turbine machines if the bushing is positioned so that it is past the end of the shaft by 1/8”, this is normal.
  6. Check the run out on the pump pulley with a dial gauge. It should be set with maximum run out of 0.005” as well. Measure on the machined v-belt surfaces. The pump pulley has only two adjustment bolts and it may be necessary to adjust the run out using ¼” bolts in the removal bolt holes.
  7. Install the correct v-belts on the machine. B37 for 24” turbine machines and B40 for 30” turbine machines. Check that the belts are not touching the plastic pump manifold.
  8. The belts are tensioned using the two ½” tensioning bolts attached to the pump feet. These bolts must be turned equally to prevent twisting of the pump. If the pump is twisted, it is possible to break the pump feet or pump housing. The bolts, which mount the pump, should be snug when tensioning. Snug enough to allow the pump to slide but limit excess movement.
  9. Tension the belts. Check that the pulleys are in line and the shafts are parallel using a straight edge. Rotate the belts and pulleys to allow belts to seat properly. This gives a more accurate reading of tension.
  10. The tension should be set as follows: Belt tension – 1/8” deflection at 7 ½ lbs force.
  11. Repeat the tensioning steps 7-10 until the correct tension is set and the pulleys are correctly lined up.