A conveyor belt is driven by a motor, via a compound gearbox and a belt drive.

The gearbox has an efficiency of 90% and the speed reduction ratio 25:1. The

belt drive has an efficiency of 96% and the speed reduction ratio 2:1. The

conveyor drum requires a torque of 550 Nm at approximately 58 rpm. The belt

conveyor operates for 12 hours per day and assume the load is gradually

applied.

2.1

Motor

(1) Calculate the rotational speed required by the motor.

(ii) Calculate the power required by the motor.

(iii) Select a suitable 3-phase Brook Crompton motor for the system

stating the following:

Motor frame size:

Motor power:

Motor speed:

Motor shaft diameter:

2.2

Coupling

For the selection of Fenaflex flange coupling:

i Determine the service factor Ks, the design power Pp and the

suggested coupling size.

ii Calculate the design torque To and the maximum design torque

Tdmax required.

(iii) Select and check the suitable coupling to be used by stating the

following:

nominal torque & maximum torque

maximum speed

coupling type

maximum bore size

2.3 Gears

The details of the gearbox are shown in Fig 2A. The two smaller (gears

1 and 3) have 18 teeth each, and gear 4 is 4 times larger than gear 2. All

the four gears have module of 4 mm and pressure angle of 20°.

Calculate the following:

1) The number of teeth, and pitch diameter of gear 2.

2) The tangential force between gears 1 and 2.

3) The separating force and resultant force between gears 1 and 2.

4) The centre distance between gears 3 and 4.

2.4 Shaft

Assume forces acting on drum shaft is shown in the free body diagram

Fig 2B. Given that the torque transmitted by the gear shaft is 581 Nm

and the load is applied gradually, determine the shaft diameter (1st

choice) assume commercial steel shaft and all components are keyed to

the shaft.