VARISCO J - Page 10

13.10 Replacing the TWIN-DISC coupling blocks (RBD series)
- Remove the pump from its seat
- Remove the worn blocks and replace them with new ones
- Check the state of wear of the aluminium flange
- Couple the pump to the engine
- Maximum alignment error: 0.7 mm
- When ordering spare rubber blocks, specify the shaft diameter and the type of coupling.
13.11 Replacing the rubber collar of SURE-FLEX couplings
- Unscrew the anchor bolts at the base of the pump or motor and separate the two halves
of the coupling
- Remove the worn rubber collar and replace it with a new one. In the case of two piece
rubber collars (type S) leave the steel ring free to move in one of the two grooves near
the indentation
- Move the pump towards the motor and fit the indentation of the half coupling to that of
the rubber collar
- Close the coupling leaving an axial play of 2 mm max. for type J couplings and 3 mm
max. for type S couplings
- Check the radial and angular alignment as follows:
Radial: (fig. 23) with a ruler placed on the outer surface of the half couplings, measure the
maximum misalignment (dimension C) in at least four points around the circumference and
try to bring it as close as possible to zero (see table)
- Angular: (fig. 23) with a gauge, measure at a minimum of four points the distance between
the two halves of the coupling and bring the difference (b-a) as close as possible to zero
(see table)
- Tighten the anchor bolts at the base of the pump and motor
- When ordering spare parts, specify the type of coupling (stamped on the inside of the half
couplings) and the shaft diameter
13.12 Replacing the rubber dowels of BALBONI GFB flexible couplings (fig. 24)
- Unscrew the anchor bolts at the base of the pump or engine and separate the two halves
of the coupling
- Remove the worn dowels and replace them with new ones, fixing them in place with a
little adhesive
- Move the pump towards the engine until the coupling is completely closed, then draw it
back by 2-3 mm to separate the two halves of the coupling
- Tighten the bolts which anchor the pump and engine to the base plate
- When ordering dowels, specify the diameter of the shaft and the type of coupling
14 OPERATING PROBLEMS: CAUSES AND REMEDIES
Attention: before examining the possible causes of operating problems, ensure
that all control instruments (vacuum gauge, pressure gauge, revolution counter,
flow recorder, electrical gauges etc.) are working correctly.
14.1 The pump does not prime
1 The pump casing is empty or non sufficiently full
fill the pump casing through the priming cover or plug (fig. 9)
2 The liquid inside the pump casing is overheated
add cold liquid to the pump casing through the priming cover or plug (fig. 9)
3 Air leaks in the joints or cracks in the suction line
Check that couplings and clamps are tight and inspect the suction line
4 Delivery line under pressure
bleed the delivery line
5 Low rotation speed of the pump
increase the speed only after having verified the contract data and the pump performance curve
6 The impeller is worn or broken
check the state of the impeller through the impeller inspection cover (26) (fig. 10), or remove the pump casing as described in
paragraph 14.2
7 The cutwater (leading edge of the volute) is worn
remove the casing as described in paragraph 14.2. Build up the cutwater with weld and shape it to restore the original profile. If the cutwater
is severely damaged, replace the casing.
8 The suction strainer (if fitted) is clogged
remove the obstructions
9 The suction lift is too high
reduce the suction lift
10 Air enters through the mechanical seal
disassemble the seal and clean it (see paragraph 14.5, 14.6); if the problem persists, change the seal
fig. 23
Half coupling
Half coupling
Rubber collar
Coupling C (b-a) Torque
type mm mm N m
J4
0,25 1,1 10
J5 0,4 1,4 20
S6 0,4 1,8 40
S7 0,5 2,1 70
Coupling type Max torque kgm rpm
14
15 4800
20 25 4400
27 40 4100
40 60 3500
55 80 3300
88 110 3000
110 150 2700
145 190 2500
180 240 2200
250 300 2150
330 400 2000
fig. 24
rubber dowel
10
Coupling
type
8 S
10 S
10 SS
11 S
14 S
Max.
speed
(RPM)
Cont.
duty
Intermitt.
duty
4500
4000
4000
3500
2800
17
31
31
48
94
2
30
30
62
121
Max. torque dNm