The ISO standard 4301-1:1988 and FEM rule 9.511/86 make is possible to classify the service group of the drive units for the trolley and end trucks

 1st - Degree of Mechanical Stress

The state of stress is evaluated considering the average entity of the loads lifted and is ascribable to one of the four spectrums load

2nd - AVERAGE DAILY OPERATION TIME

For Driving operations is calculated as follows:

 Tm (hours) = (ADR x C/h x Rt) / (30 x S)

 Where:

 ADR : Actual Drive Run

 C/h : N° of  complete strokes traveled

 Rt : Drive running time in whole day 

 S : Running Speed