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

ISRB

 2005 GEA 20260

Page 7 of 24

of twist. The slab must be provided with suitable 

anchor bolts. The use of grouting under and partly 

inside the leveled and shimmed base is 

recommended. 
It is possible for a base-mounted assembly to 

become twisted during shipment, thus disturbing the 

original alignment. For this reason, make the 

following checks after the base has been leveled and 

bolted down. Disconnect the drive and rotate the unit 

shaft by hand. It should turn freely at all points. 

Loosen the unit foot hold-down screws and determine 

whether all feet are evenly in contact with the base. If 

not, insert shims as required and again check for free 

impeller rotation. Finally, if unit is direct coupled to 

the driver, check shaft and coupling alignment 

carefully and make any necessary corrections. 
In planning the installation, and before setting the 

unit, consider how piping arrangements are dictated 

by the unit design and assembly. Drive shaft rotation 

must be established accordingly and is indicated by 

an arrow near the shaft. 
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 2, page 9 in the 2500 Series Whispair 

Max Section, Table 3, page 9 in the DVJ Section for 

allowable speeds of various unit sizes. 
A flexible type coupling should always be used to 

connect the driver and unit shafts. 
When direct coupling a motor or engine to a blower 

you must ensure there is sufficient gap between the 

coupling halves and the element to prevent thrust 

loading the blower bearings. When a motor, engine 

or blower is operated the shafts may expand axially. 

If the coupling is installed in such a manner that there 

is not enough room for expansion the blower shaft 

can be forced back into the blower and cause the 

impeller to contact the gear end headplate resulting 

in damage to the blower. The two shafts must be in 

as near perfect alignment in all directions as possible, 

and the gap must be established with the motor 

armature on its electrical center if end-play exists. 
Coupling manufacturer’s recommendations for 

maximum misalignment, although acceptable for the 

coupling are normally too large to achieve smooth 

operation and maximum life of the blower. 

The following requirements of a good installation are 

recommended. When selecting a coupling to be fitted 

to the blower shaft Howden Roots recommends a 

taper lock style coupling to ensure proper contact 

with the blower shaft. Coupling halves must be fitted 

to the two shafts with a line to line thru .001” 

interference fi t. Coupling halves must be warmed up 

per coupling manufacturer’s recommendations. 

Maximum deviation in offset alignment of the shafts 

should not exceed .005” (.13 mm) total indicator 

reading, taken on the two coupling hubs. Maximum 

deviation from parallel of the inside coupling faces 

should not exceed .001” (.03 mm) when checked at 

six points around the coupling. 
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 Howden 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 fi t to the shaft of the 

blower (set screw types of attachment generally do 

not provide reliable service.) 

ISRB 2005 GEA 20260.indd   7

17/09/2015   12:53