Calculations for stresses in the platform members (and doors) of freight elevators are based on the following concentrated loads assumed to occupy the position which will produce the maximum stress:
Class A loading – General freight loading: Load is handled on and off the car platform manually or by means of hand trucks. Single piece of freight not more than 25% of rated load.
Class B loading: Where the elevator is used solely to carry automobile trucks or passenger automobiles up to the rated capacity of the elevator.
Class C1 – Industrial truck loading: Where the static load during loading and unloading does not exceed the rated load
Class C2 – Industrial truck loading: Where the static load during loading and unloading is permitted to exceed the rated load.
Class C3 – Other loading with heavy concentrations: Where the static load during loading and unloading does not exceed the rated load.