Shaft Mounted Speed Reducer; Selection Procedure

Shaft Mounted Speed Reducer Selection Procedure

Shaft Mounted Speed Reducer; Selection Procedure

1) Service Factor.

From Table 1, select the service factor that is appropriate for the application.

2) Design Power.

Multiply the absorbed power of the driven machine by the service factor, from step 1) to obtain the design power. If the absorbed power is not known, use the motor power.

3) SMSR gear unit size selection.

Refer to the power rating tables (Tables 2), then read down the left hand vertical column to the required output speed. (interpolate if the exact speed is not listed).

Read horizontally across on the speed line until a power equal to or in excess of the design power, from step 2), is reached.

Read vertically to the top of the column to obtain the correct size of SMSR unit.

The ratio of the chosen unit is determined by the required output speed.

Refer to Table 3 in order to check that the chosen SMSR will fit the driven machine shaft.

 

Service Factor

Table 1 - Service Factors

 

Power Ratings Single

Table 2a - Power Ratings (Single Reduction)

 

Power rating double

Table 2b - Power Ratings (Double Reduction)

 

Hub Bores

Table 3 - Hub Bores

 

Wedge belt drive selection procedure.

 

Two methods are used for the belt drive selection.

One for 1440 rev/min electric motors and secondly for all other speeds.

 

1440 rev/min electric motor speed.

a) Output speed.

Refer to the Wedge belt drive selection tables at the end of this article for the chosen gear unit size. Read down the left-hand column headed ‘output speed’ until a speed equal to or near to that required is found.

b) Pulley pitch diameters.

Read across from the chosen output speed to obtain the pulley diameters for the motor shaft and SMSR input shaft.

On smaller size gear units, it may well be that single belt drives are recommended. If, on such drives, two belts are preferred, special attention must be made to belt tensioning.

If in any doubt, please contact CHALLENGE.

c) Centre distance.

Refer to our previous technical articles on Wedge Belts to calculate the correct belt length for the required centre distance.

 

Other prime mover speeds

a) SMSR unit input shaft speed.

Multiply the chosen SMSR gear unit output speed by its exact speed ratio to obtain the SMSR gear unit input shaft speed.

The exact gear ratio of the chosen SMSR can be found at the bottom of the SMSR dimension table which is provided at the end of this article.

b) Selection of wedge belt drive.

The correct wedge belt can be designed by referring to our previous technical articles on wedge belt calculations.

 

Shaft Mounted Speed Reducer selection example

 

Select a Challenge Shaft Mounted Speed Reducer to drive a rotary kiln which absorbs 0.95 kW when running at 20 rev/min for upto 8 hours/day.

The prime mover is a 1.1 kW, 1440 rev/min electric motor with a star-delta starter and a 24 mm shaft.

The kiln has a 50 mm shaft and 450 mm drive centres are required.

 

1) Service Factor.

From Table 1, the chosen service factor is 1.25.

2) Design Power.

Using the kiln absorbed power of 0.95 kW, the design power is;

0.95 x 1.25 = 1.19 kW

3) SMSR gear unit size selection.

From the SMSR power rating Table 2, a size D13 or D20 will transmit 1.58 kW at 20 rev/min which is in excess of the required 1.19 kW from step 2).

A size D20 rather than a D13 is chosen as it will utilize a more economically priced Wedge belt drive.

On checking the hub sizes on in Table 3, it is seen that the D20 has a 50 mm standard hub bore which matches the kiln shaft of 50 mm.

 

Wedge belt drive selection procedure.

 

As the motor speed is 1440 rev/min, the following selection method is used :-

 

1440 rev/min electric motor speed.

a) Output speed.

Refer to the Wedge belt drive selection tables at the end of this article for SMSR size ‘D’ units.

Read down the left hand column to required output speed of 20 rev/min.

b) Pulley pitch diameters.

Read across from the chosen output speed to obtain the prime mover and SMSR input shaft pulley diameters. The electric motor to be fitted with a 71 x 1 SPZ pulley and the SMSR input shaft with a 250 x 1 SPZ

c) Centre distance.

Referring to previous wedge belt calculation articles (Blog -> Technical -> Belting) and by using the appropriate formulae, an SPZ1420 will give a centre distance of 449 mm.

 

Drive Specification.

 

SMSR size: D20 with a standard hub bore of 50 mm

Motor pulley: 71 x 1 SPZ with taper bush size 1108 bored 24 mm

SMSR input shaft pulley: 250 x 1 SPZ with taper bush 2012 bored 25 mm

An SPZ1420 Wedge belt gives a centre distance of 449 mm.

 

Shaft Mounted Speed Reducer Dimensions

 

SMSR Dimensions Diagram

SMSR Dimensions

Wedge Belt Drives for 1440 rev/min Electric Motors

 

Wedge Belt Drives Table 1

Wedge Belt Drives Table 2

Wedge Belt Drives Table 3

Wedge Belt Drives Table 4

Wedge Belt Drives Table 5

Wedge Belt Drives Table 6

Wedge Belt Drives Table 7

Wedge Belt Drives Table 8

Wedge Belt Drives Table 9

Share: