Howden Roots 2500 Series WHISPAIR MAX, Installation, Operation And Maintenance Manual

ISRB

 2005 GEA 20260

Page 9 of 24

When a unit is BELT DRIVEN, the proper selection of 

sheave diameters will result in the required unit 

speed. When selecting a sheave to be fitted to the 

blower shaft ROOTS recommends a taper lock style 

sheave to insure proper contact with the blower shaft. 

This flexibility can lead to operating temperature 

problems caused by unit speed being too low. Make 

sure the drive speed selected is within the allowable 

range for the specific unit size, as specified under 

Table 2, page 9 in the 2500 Series Whispair Max 

Section, Table 3, page 9 in the DVJ Section. 
Belt drive arrangements should employ two or more 

3V, 5V, or 8V-belts running in grooved sheaves. 

Installation of the driver is less critical than for direct 

coupling, but its shaft must be level and parallel with 

the unit shaft. 

The driver should be mounted on 

the inlet side of a vertical unit (horizontal piping) 

and on the side nearest to the shaft on a 

horizontal unit. (See page 7 for acceptable V belt 

drive configurations.)

 The driver must also be 

mounted on an adjustable base to permit installing, 

adjusting and removing the V-belts. To position the 

driver correctly, both sheaves need to be mounted on 

their shafts and the nominal shaft center distance 

known for the belt lengths to be used. 

CAUTION

: Drive couplings and sheaves (pulleys) 

should have an interference fit to the shaft of the 

blower (set screw types of attachment generally do 

not provide reliable service.)  
It is recommended that the drive coupling or sheave 

used have a taper lock style bushing which is 

properly sized to provide the correct interference fi t 

required. Drive couplings, that require heating to fi t 

on the blower shaft, should be installed per coupling 

manufacturer recommendations. A drive coupling or 

sheave should not be forced on to the shaft of the 

blower as this could affect internal clearances 

resulting in damage to the blower. Engine drive 

applications often require special consideration to 

drive coupling selection to avoid harmful torsional 

vibrations. These vibrations may lead to blower 

damage if not dampened adequately. It is often 

necessary to install a fl y-wheel and/or a torsionally 

soft elastic element coupling based on the Engine 

manufacturer recommendations. 
When a unit is DIRECT COUPLED to its driver, the 

driver RPM must be selected or governed so as not 

to exceed the maximum speed rating of the unit. 

Refer to Table 1 for allowable speeds of various unit 

sizes. 
The driver sheave should also be mounted as close 

to its bearing as possible, and again should fi t the 

shaft correctly. Position the driver on its adjustable 

base so that 2/3 of the total movement is available in 

the direction away from the unit, and mount the 

assembly so that the face of the sheave is accurately 

in line with the unit sheave. This position minimizes 

belt wear, and allows sufficient adjustment for both 

installing and tightening the belts. After belts are 

installed, adjust their tension in accordance with the 

manufacturer’s instructions. However, only enough 

tension should be applied to prevent slippage when 

the unit is operating under load. Excessive tightening 

can lead to early bearing failures or shaft breakage. 
Before operating the drive under power to check 

initial belt tension, first remove covers from the unit 

connections. Make sure the interior is still clean, and 

then rotate the shaft by hand. Place a coarse screen 

over the inlet connection to prevent anything being 

drawn into the unit while it is operating, and avoid 

standing in line with the discharge opening. Put oil in 

the sumps per instructions under LUBRICATION.

Piping 

Before connecting piping, remove any remaining anti-

rust compound from Unit connections. Clean pipe 

should be no smaller than unit connections. In 

addition, make sure it is free of scale, cuttings, weld 

beads, or foreign material of any kind. To further 

guard against damage to the unit, especially when an 

inlet filter is not used, install a substantial screen of 

16 mesh backed with hardware cloth at or near the 

inlet connections. Make provisions to clean this 

screen of collected debris after a few hours of 

operation. It should be removed when its usefulness 

has ended, as the wire will eventually deteriorate and 

small pieces going into the unit may cause serious 

damage. 
Pipe flanges or male threads must meet the unit 

connections accurately and squarely. DO NOT 

attempt to correct misalignment by springing or 

cramping the pipe. In most cases this will distort the 

unit casing and cause impeller rubbing. In severe 

cases it can prevent operation or result in a broken 

drive shaft. For similar reasons, piping should be 

supported near the unit to eliminate dead weight 

strains. Also, if pipe expansion is likely to occur from 

ISRB 2005 GEA 20260.indd   9

17/09/2015   12:53