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Johnson Controls Denmark ApS
Christian X's Vej 201 ∙ 8270 Højbjerg ∙ Denmark
Phone +45 87 36 70 00 ∙ www.sabroe.com
CVR No 19 05 61 71
Mounting instruction
0010561
03 November 2020
Mounting of BPU coupling on SAB 193, 233 and 283 screw compressors
Fig. 1
1. Inspect shafts and hubs to make sure they are free from burrs.
2. Fit the key to the shaft.
Note: Never tighten the clamp bolts without the hub mounted onto the appropriately sized shaft. Also, do not
tighten the set screw before the clamp bolts. Make sure it is not engaging the top of the key before proceeding to
step 3.
Apply a light oil film on all contact surfaces. Do not use any oil with molibdenum bisulphite or high-pressure addi-
tives and do not use grease. These substances notably reduce the friction coefficient.
3. With the clamp bolts loose and the set screw slightly unscrewed, install the motor and compressor coupling
hubs and key on their respective shafts.
4. Make sure they can slide horizontally so that once the disc packs are installed, no axial stress is transferred
to the disc packs by a stuck coupling hub.
5. Rotate both hubs so that the keys are 180 degrees opposite each other.
Set
Disc pack
Hub clamping bolts
Set screwKeyways located
180° opposite
lock nuts
screw
G G
A
Page 2 of 3
Johnson Controls Denmark ApS
Christian X's Vej 201 ∙ 8270 Højbjerg ∙ Denmark
Phone +45 87 36 70 00 ∙ www.sabroe.com
CVR No 19 05 61 71
6. With the hubs mounted and the axial spacing set, proceed to place the spacer between the two hub flanges.
Be careful when handling the spacer.
Make sure the spacer is fully supported.
If the spacer is not fully supported, the unitised flex discs may be damaged after installation.
7. Install the unitised flex disc now.
Make sure that all bolt threads are clean and lightly oiled.
8. Start a bolt through a bolt hole in the spacer.
9. Put the unitised flex disc between the hub and spacer until a bushing hole in the unitised flex disc lines up
with the bolt.
10. Slide the bolt through the bushing hole in the unitised flex disc.
11. Install the lock nut until it is snug.
Do not torque any lock nuts at this time.
12. The remaining bolts for this end of the coupling can be installed through the hub bolt holes and flex disc
bushing holes.
13. Install the unitised flex disc in the other end of the coupling. The unitised flex disc, as installed, should look
flat and parallel with the mating hub and spacer flanges.
14. Torque the disc pack lock nuts as recommended in Table 1. Hold the bolts in place while the lock nuts are
torqued. Turning the bolts will damage the flex disc.
15. Centre the coupling between the shafts. Make sure that the keys are fully engaged in their keyways.
The average gap dimension ‘G’ as shown in Fig. 1 at each disc pack should be within the value given in Table 1
+/-12.5% of the axial capacity of the coupling.
16. To improve the coupling installation and performance, it is recommended, if possible at this stage, to rotate
the assembly a few times while repeatedly rapping the spacer flange OD with a soft dead blow hammer to
relieve any binding in the disc packs.
BPU
series
Disc pack
lock nut Hub clamping bolts Keyway
set screw
torque
(Nm)
Size NC
Clamp
bolts ‘A’ dia.
(mm)
‘G’
(mm)
Coupling ax-
ial
capacity
(mm)
Torque
(lube)
(Nm)
Size UNF Torque
(Nm) Size UNF Size UNF
BPU-38 30 5/16-24 14.9 1/4-28 30 3/8-16 1/4-28 149 10.2 ± 0.71
BPU-41 75 7/16-20 31.2 5/16-24 30 3/8-16 5/16-24 162 14 ± 0.74
BPU-47 162.7 9/16-18 55.6 3/8-24 68 1/2-13 3/8-24 183 15.7 ± 0.76
BPU-54 162.7 9/16-18 89.5 7/16-20 68 1/2-13 7/16-20 208 15.7 ± 1.27
BPU-56 162.7 9/16-18 136.9 1/2–20 68 1/2-13 1/2-20 222 15.7 ± 2.03
Table 1: BPU series coupling data
G: The distance between spacer and coupling hub, both sides. See Fig. 1
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Johnson Controls Denmark ApS
Christian X's Vej 201 ∙ 8270 Højbjerg ∙ Denmark
Phone +45 87 36 70 00 ∙ www.sabroe.com
CVR No 19 05 61 71
Fig. 2: Clamp hub design
Tighten the clamp screws in three stages. With each stage, follow the tightening sequence pattern shown in section
A-A in Fig. 2.
1. Hand tighten with an Allen wrench.
2. Tighten to half the clamp screw tightening torque value shown in Table 1 (according to the coupling size).
3. Tighten to the full clamp screw tightening torque value shown in Table 1 according to the coupling size. Con-
tinually repeat the tightening sequence of section A-A until all bolts are completely tightened. Tighten the
set screw per the appropriate value shown in Table 1 according to the coupling size.
Erhardt Nielsen
Manager, Compressor Development
Engineering, Industrial Refrigeration (IR), Product Technology, Denmark
Building Technologies & Solutions
Tel: +45 87 36 77 20
Mob: +45 29 22 77 20
E-mail: [email protected]
www.sabroe.com
Section A-A
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