Steelcase Con-Centrx 451-141 User manual

Steelcase, Inc.
Grand Rapids, MI 49501
U.S.A.
1-888-783-3522
Tools
Assembly Directions Printed In U.S.A.
REV
93-9501164 B
Page 1 of 6
For Field Replacement of the Variable
Back Locking Mechanism - Package
Number 25-4540800
These directions apply to the following Con-Centrx® chair models:
Managerial chair: 451-141, 141M, 171, 171M, 147, 147M, 177 and 177M
Operator chair: 454-150, 150M, 180, 180M, 151, 151M, 152, 152M, 181, 181M, 182 and 182M
IMPORTANT: Please read these directions completely through prior to starting step 1
A
W
L
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O
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P
O
W
E
R

Assembly Directions
93-9501164 REV B Page 2 of 6
Mechanism Operation:
When the variable back locking mechanism is operating properly, the following actions will occur:
1. With the back attitude control button in the forward position (towards the front of the chair) the chair will tilt.
2. When you do not want the chair to tilt, move the button to the rear and the back will lock in any attitude. Control
button should always clear outer plastic seat shell and actuation force should not be excessive.
Variable Back Attitude Replacement and Mechanism Adjustment:
Should the chair fail to perform satisfactorily in any of the functions described above check adjustment per step 8.
If adjustment is satisfactory and the variable back locking mechanism is not operating properly, replace according
to steps 1 thru 11.
Package Contents
HOUSING AND
GEAR ASSEMBLY
(2) 5/8” RETAINER RINGS
(2) PIVOT BUSHINGS
OVERCENTER
SPRING
RETAINER
RING
1/4” PIN
PAWL
1/4” RETAINER RING
ADJUSTABLE
CONTROL ARM
U-JOINT
ASSEMBLY
U-JOINT PIN
LUBRIPLATE OR
AMOCO GREASE PACK

Assembly Directions
93-9501164 REV B Page 3 of 6
1. Place the chair on a clean padded workbench in
an inverted position. Remove (5) #8 screws, (2)
#10 screws and outer back shell from upholstered
back. NOTE: Extreme care should be taken with
the screwdriver when removing screws to prevent
damage to the outer plastic shell. #10 SCREWS
1/2” LONG
OUTER BACK
SHELL
#8 SCREWS
1-1/2” LONG
#8 SCREW
1-1/8” LONG
UPHOLSTERED
BACK
VARIABLE BACK
LOCKING
MECHANISM
IMPORTANT: THIS CIRCLED
AREA INDICATES THE LOCATION
FOR THE FOLLOWING STEPS 2,
3, 4, 5 and 6

Assembly Directions
93-9501164 REV B Page 4 of 6
2. Remove adjustable control arm from pawl by using a 1/4” flat-bladed screwdriver to pry the rearward half of the
control arm which has a snap fit on the pawl. Snap off forward half of control arm by hand. Save adjustable
control arm for the adjustment of new control arm. Old removed parts are not to be used.
ADJUSTABLE
CONTROL ARM
3. Remove the retainer ring from the end of the pivot pin by using the flat-bladed screwdriver and slide pin out.
Remove overcenter spring and pawl from lower mounting bracket.
Old removed parts are not to be used.
PAWL
ADJUSTABLE
CONTROL ARM
RETAINER RING
OVERCENTER
SPRING
PIVOT PIN
PAWL

Assembly Directions
93-9501164 REV B Page 5 of 6
4. Remove the retainer rings from pivot bushings
by using the flat-bladed screwdriver and slide
out pivot bushings and discard.
5. Turn housing and gear assembly clock-wise
while at he same time lifting up thus removing
it from the chair. Old removed parts are not
to be used.
6. Remove retainer ring from the end of u-joint
pin by using a flat-bladed screwdriver. Slide
pin out and remove u-joint assembly.
RETAINER RINGS
PIVOT
BUSHING
PIVOT
BUSHING
HOUSING AND
GEAR ASSEMBLY
HOUSING AND
GEAR ASSEMBLY
RETAINER
RING
U-JOINT
ASSEMBLY
U-JOINT
PIN

7. Turn new u-joint assembly upright and fill with Lubiplate or Amoco grease.
Make sure the new adjustable control arm is adjusted the same length as the
old one just removed. NOTE: The adjustable control arm is adjusted so the
control button clears the front edge of outer seat shell 1/8” when front slide
control is adjusted in the down position. Reverse the disassembly procedure
steps 6 thru 2 only and assemble the new parts.
NEW ADJUSTABLE
CONTROL ARM
Assembly Directions
93-9501164 REV B Page 6 of 6
EXISTING DIMENSION FOR
OLD ADJUSTABLE CONTROL ARM
LUBRIPLATE OR
AMOCO GREASE
U-JOINT
ASSEMBLY
8. Place the chair upright on the floor. Check the chair to verify that all functions are operating properly. Invert the
chair back onto workbench and reassemble the outer back shell onto upholstered back. This step is in reverse of
step 1, page 3 of these directions. You may wish to use an awl to find the existing screw holes on the inner back
assembly. Proper positioning is required for function appearance.
CONTROL
BUTTON
1/8”
FRONT
SLIDE
CONTROL