BULLETIN A-3037
P-222-32
Installation Instructions
Backstop Clutches
Models FB
23601 Hoover Road - W
arren, MI 48089-3994 - 586-758-5000
www.formsprag.com
Introduction
1/4"
FAN SHAFT
TORQUE ARM STOP
KEY
HOUSING SNAP RING
CSK CLUTCH
STUB SHAFT
C-RING ASSEMBLY
STUB SHAFT
CAPSCREW (4)
(5/16-24 THREAD)
FREE ROTATION
ARROW
RETAINER PLATE
CAPSCREWS (2)
(1/4-20 THREAD)
RETAINER PLATE
C-RING CAPSCREW (2)
(3/8-24 THREAD)
SHIM (2)
DOWEL PIN (2)
REMOVE
AT ASSEMBLY
Formsprag model FB Backstops combine a CSK
sprag clutch having its own ball bearing with integral
seals, a torque arm housing, stub shaft adapter (stub
shaft) and clamping assembly (C-Ring Assembly).
This design prevents reverse rotation of shafts in
applications with large shafts and low back stopping
torque requirements. Clutches are selected by torque
capacity and shaft size.
Failure to follow these instructions
may result in product damage, equipment damage,
and serious or fatal injury to personnel.
Figure 1
Formsprag Clutch • 800-927-3262 Bulletin A-3037
2
Pre-Installation Instructions
Review Figure 1 to identify the nomenclature for the
various components of the model FB Backstop.
Remove the retainer plate from the stub shaft
adapter by removing the 1/4-20 flat head screws.
lide the backstop housing off the stub shaft adapter.
S
etain the key and screws for later reassembly.
R
If you have ordered a Backstop with the bore
machined by Formsprag proceed to item 2. If the
backstop was purchased from the factory as a rough
bore, both the C Ring and stub shaft adapter need to
be machined as follows:
1. Bore Machining Instructions
a. C-Ring Assembly. The C-Ring assembly
comes with 0.125” shims installed between
the C-ring halves. Machine the CRing
assembly as a unit with the shims installed
to the maximum size of the mating shaft
diameter with a tolerance of 0.000”
to 0.001”. The surface finish of the
machined C-Ring bore should be 30 to 45
micro Ra. Skim cut the C-Ring face with the
threaded holes in the same chucking as the
boring operation.
b. Stub shaft. Machine the face opposite the
stub shaft with a blind counter bore to the
maximum size of the mating shaft diameter
with a tolerance +0.001” to +0.002” and a
depth of 0.250”. Machine a 15 degree lead
in chamfer on the counter bore to a depth
not to exceed 0.062”. The run out (TIR)
between the counter borediameter and the
stub shaft diameter must be less than 0.002”.
2. Mating Fan Shaft and Torque Arm Requirements.
Befor
e installing the backstop, check the
following:
a. Mating Shaft. The mating shaft of the
assembly needs to be round within 0.001”
and machined to a surface finish of less
than 45 micro Ra. The tolerance of the
mating shaft is nominal +0.000” to – 0.001”.
b. Torque arm stops. Ensure that appropriate
equipment frames or structur
for fastening stops for the backstop’s torque
arm as shown in the Figure 1.
es are available
Installation
. Dry assemble all components to the fan shaft
1
before completing the assembly with Loctite®to
ensure proper fit.
2. Disassemble the C-Ring assembly into two
halves by removing two 3/8-24 socket head cap
screws. Remove but do not discard the shims.
3. Apply Loctite®262 to the two 3/8-24 socket
head cap screw threads.
4. Reassemble the C-Ring assembly on the fan
shaft with the machined face out. Place the
shims between the C-Ring halves and outside
the dowel and screw holes. The shims will
project out of the C-Ring. Lightly tighten the
socket head cap screws applying just enough
pressure on the shims so they do not fall out
but still can be repositioned.
5. Slide the stub shaft onto the fan shaft. Position
the C Ring assembly by sliding until it mates
against the back face of the stub shaft. Remove
the stub shaft. Tap the CRing toward the shaft
end 1/16 of inch to ensure that the stub shaft
will seat against the C-Ring and not the fan
shaft end. The fan shaft will project 0.200” to
0.250” beyond the C-Ring when positioned
correctly.
6. Without repositioning the C-Ring, remove the
shims and torque down the fasteners a quarter
turn at a time, alternating from one fastener to
the other to tighten the C-Ring evenly. Torque
the 3/8-24 screws to 300 – 450 inch-pounds.
Note: Individually tightening the screws one at
a time to the specified torque will
damage the C-ring and not provide
adequate clamping to the shaft.
7. Slide the stub shaft on the mating shaft. Place
the flat washers on the 5/16-24 screws. Apply
Loctite 262 to the four 5/16 – 24 socket head
cap screw thread and thread them through the
holes in the stub shaft and into the C-Ring,
hand tight.
8. Verify that the stub shaft is concentric with the
fan shaft by keeping the run out on the stub
shaft to within 0.002 in. TIR.
Formsprag Clutch • 800-927-3262 Bulletin A-3037
3
9. Tighten the four 5/16-24 socket hed cap screws
to 200-240 inch pounds.
10. Apply Loctite®262 to the torque arm and thread
torque arm into the housing. Hand tighten the
torque arm until fully seated.
Note: Verify shaft rotation before installing
torque arm housing to the stub shaft.
Verify that shaft rotation is in the direction
of the arrow on the torque arm housing.
11. Coat the stub shaft with anti seize compound.
Install the key into the keyway of the stub shaft,
and slide the torque arm housing on to the stub
shaft. Assemble the bearing retainer plate to the
stub shaft. Tighten the 1/4-20 flat head screws
to 100 to 120 inch pounds.
10. Attach torque arm stops to equipment frame or
supporting structur
prevent rotation of torque arm when holdback
torque is applied. Allow clearance between
stops and torque arm as shown in the figure.
Make sure the torque arm stops can handle the
rated torque of the backstop. DO NOT RIGIDLY
MOUNT THE TORQUE ARM. DO NOT WELD,
CLAMP
ARM – ALLOW THE TORQUE ARM TO FLOA
The clearance is necessary to permit free axial
and angular movement of the torque arm
resulting from shaft run out and eccentricity.
, FASTEN OR FIX THE TORQUE
e. The stops are required to
T.
Lubrication and Maintenance
. The model FB comes lubricated for life.
1
CONTACT FORMSPRAG FOR REPLACEMENT
TORQUE ARM HOUSING
2. Replace the torque arm housing sprag clutch
every five years to ensure uninterrupted service
life. The torque arm housing replacement part
number for FB-100 and FB-350 is “FBREPAIR”
and for FB-450 is “FBREPAIR-1”. Follow the
instructions below:
a. Remove the bearing retainer.
b. Slide the torque arm housing off the stub
shaft adapter.
c. Re-install the torque arm housing following
the installation procedure starting at step 10.
Rotating Equipment
Rotating Equipment is potentially dangerous and
should be properly guarded. The user should check
for all applicable safety codes (in local area) and
provide a suitable guard. For Application Assistance
call 1-800-927-3262.
Note: Torque arms may be installed at any
angle, however, vertical torque arms
should be installed at least 10 degrees
from the true vertical position.
Vibration Troubleshooting
1.
If unacceptable levels of vibration occur upon
installation, disassemble and reinstall being sure
to tighten fasteners as described, and verify that
the stub shaft adapter sits flush with the C Ring
assembly not bottomed out against the mating
shaft. Also verify that the torque arm is not
bound in any way but is free to float against its
stops.
2. V
erify that the stub shaft diameter runout does
not exceed 0.002 TIR. For minimal vibration
reduce the runout to 0.000 TIR or as close as
possible.
Formsprag Clutch • 800-927-3262 Bulletin A-3037
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Formsprag Clutch • 800-927-3262 Bulletin A-3037
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Warranty
Formsprag LLC warrants that it will r
r
eplace (whichever in its sole discretion it deems
advisable) any product it manufactured and sold
which proves to be defective in material or
workmanship within a period of one (1) year
from date of original purchase for consumer,
commercial or industrial use. This warranty
extends only to the original purchaser and is not
transferable or assignable without Formsprag
LLC’s prior consent.
This warranty covers normal use and does not
cover damage or defect which results from alterations, accident, neglect, disassembly, or
improper installation, operation, or maintenance.
Formsprag LLC’s obligation under this warranty
is limited to the repair or replacement of the
defective pr
oduct. In no event shall Formsprag
LLC be liable for consequential, indirect or incidental damages of any kind incurred by reason
of manufacture, sale or use of any defective
product. Formsprag LLC neither assumes nor
authorizes any other person to give any other
warranty or to assume any other obligation or
liability on its behalf.
epair or
For
msprag Clutch
23601 Hoover Road • Warren, MI 48089
586-758-5000
P-222-32 Bulletin A-3037 6/06 Printed in USA
• Fax: 586-758-5204
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