The graph shows the efficiency of a basic PIV unit, which may be taken as typical for all sizes. It will be seen that under full load conditions, this is 86% at top speed, and 95% at mean speed. With compound attachments, the efficiency is reduced by 1.5% for each pair of spur gears and between 20% and 30% for worm gears in the W portion. Capacity The power which can be transmitted at output speeds between maximum and minimum is shown in the graph by considering the speed concerned as a percentage of maximum speed. The power at this speed is then read off the graph as a percentage of the power at maximum speed. Selection Data Data required for selection of PIV unit: a) Speed Ratio b) Power or Torque at Max. or Min. speed, or Motor HP available. c) Operation conditions, e.g. running time per day, frequency of starts, uniformity of loads. Service Factor The maximum input horsepower of basic PiV units given in the rating tables are for units operating under uniform load for 12 hours per day. Where operating conditions differ, multiply the required power by the factors shown:

The graph shows the efficiency of a basic PIV unit, which may be taken as typical for all sizes. It will be seen that under full load conditions, this is 86% at top speed, and 95% at mean speed. With compound attachments, the efficiency is reduced by 1.5% for each pair of spur gears and between 20% and 30% for worm gears in the W portion. Capacity The power which can be transmitted at output speeds between maximum and minimum is shown in the graph by considering the speed concerned as a percentage of maximum speed. The power at this speed is then read off the graph as a percentage of the power at maximum speed. Selection Data Data required for selection of PIV unit: a) Speed Ratio b) Power or Torque at Max. or Min. speed, or Motor HP available. c) Operation conditions, e.g. running time per day, frequency of starts, uniformity of loads. Service Factor The maximum input horsepower of basic PiV units given in the rating tables are for units operating under uniform load for 12 hours per day. Where operating conditions differ, multiply the required power by the factors shown: