Trane SCXG-SVX01B-EN manual maintenance, Maintenance procedures, Fan BeltTension

maintenance

Maintenance procedures

Fan BeltTension

Note: Check fan belt tension at least twice during the first days of new belt operation since there is a rapid decrease in tension until belts are run-in.

Proper belt tension is necessary to endure maximum bearing and drive component life and is based on fan brake horsepower requirements. If frayed or worn, replace belts in matched sets.

Measuring BeltTension Measure fan belt tension with a Browning, Gates, or equivalent belt tension gauge. Determine deflection by dividing the belt span distance (in inches) by 64. See Figure M-MP-6. Follow the procedure below to measure belt tension.

1.Measure belt span between centers of sheaves and set the large “O” ring of the tensioning gauge at 1/64 inch for each inch of belt span.

2.Set the load “O” ring at zero.

3.Place the large end of the gauge at the center of the belt span. Press down until the large “O” ring is even with the top of the belt line or the next belt as in Figure M-MP-6. Place a straight edge across the sheaves as a reference point. See Figure M-MP-4.

4.Remove the gauge. Note that the load “O” ring now indicates a number on the plunger scale. This number represents pounds of force required to deflect the belt.

5.Check the reading from step 4 against the values given inTable M-MP-4. If necessary, readjust belt tension.

Table M-MP-4. Fan shaft bearing torques

setscrew	hex-size	recommended torque
size	across flats	In-lb	ft-lb
1/4"-20	1/8"	180	15
5-16"-18	5-32"	402	33.5

Table M-MP-5. Fan hub and sheave torques
unit	fan	setscrew	torque
size	dia.	size	(ft-lbs)
SCWF 20	16.5"	5/16"	12
SCWF 22
SCWF 25
SCRF 20
SCWF 29	18"	5/16"	12
SCWF 32
SCRF 25
SCRF 30
SCWF 35	20"	5/16"	14
SCWF 38
SCRF 30
SCRF 35
SCWF 42	25"	3/8"	24
SCWF 46
SCWF 52
SCWF 58
SCRF 40
SCRF 50
SCWF 65	27"	3/8"	24	Figure M-MP-5. Belt tension gauge

SCWF 72

SCWF 80

SCRF 60

SCWF 90

SCWF C0

SCWF C1

deflection = belt span/64

Figure M-MP-6. Fan belt adjustment

96 SCXG-SVX01B-EN