108833 Rev. C
21
S - 6 3 6 / S - 6 4 6
X. OPERATING INSTRUCTIONS
J. SEAT DEPTH
The seat depth can be adjusted in one-inch increments along the seat rail. Use holes in rail,
viewed through side channel as a guide.
NOTE–
If you intend to adjust the seat depth and the backrest pivot point (see section K) you will save time
by reviewing both sets of instructions and logically combining the steps.
To adjust seat depth:
1. Remove armrests from chair.
2. Note the specific hole positions of the actuator extension tube and the gas spring ball
socket so they can be duplicated later.
3. Remove 3/8 hex bolts (A) holding actuator extension tube into rear support plate.
IMPORTANT NOTE–
there will be significant forward pressure from the back sup-
port suspension gas spring (B). Allow this pressure to extend the gas spring to its maxi-
mum, moving the backrest forward. Once extended fully, remove the 5/16 nut secur-
ing the ball socket (C) to the lower end of the gas spring.
4. Allow back to rotate forward and rest on seat.
5. Loosen the two 1/4-28 screws (D) on the outside of both backrest pivot plates.
6. Reposition the backrest to the desired location, insuring that the rear 1/4-28 screw is
properly aligned with a guide hole in the seat rail.
NOTE–
Only the rear screw aligns
with a guide hole. Retighten screws on both backrest pivot plates.
7. When the backrest is moved horizontally, the rear actuator support plate must be
moved as well. Remove the two 5/16 bolts (E) that secure the plate and reposition in a
1:1 ratio as it relates the movement of the backrest pivot plates. Reverse orientation of
the rear actuator support plate is necessary for 14" and 15" seat depths on the stan-
dard length frame and for 18" and 19" seat depths on the long frame.
8. Rotate backrest rearward to align the gas spring with its mount, replacing the ball sock-
et in its previous position and securing with the 5/16 nut.
9. Using rearward pressure against the backrest, rotate the backrest to align the actuator
extension tube with its previous mounting position and reinstall 3/8 hex bolts.
NOTE–
this step may require assistance to complete.
K. BACKREST PIVOT POINT
The backrest pivot point can be adjusted vertically for varying cushion thickness and body
types. There are three positions available in 3/4" increments.
To adjust:
1. Remove armrests from chair.
2. Note specifically the current and intended bolt positions of the actuator and gas spring
fasteners. Your goal is to reposition both fasteners in a 1:1 ratio with the vertical move-
ment of the pivot point.
3. Remove 3/8 hex bolts (A) holding actuator extension tube into rear support plate.
IMPORTANT NOTE–
there will be significant forward pressure from the back sup-
port suspension gas spring (B). Allow this pressure to extend the gas spring to its maxi-
mum, moving the backrest forward. Once extended fully, remove the 5/16 nut secur-
ing the ball socket (C) to the lower end of the gas spring.
4. Allow back to rotate forward and rest on seat.
5. Using a 7/16 socket, remove hex bolts (D) and reposition assembly up or down for
desired affect.
6. Rotate backrest rearward to align the gas spring with its mount, replacing the ball sock-
et in the appropriate position (review step 2) and securing with the 5/16 nut.
7. Using rearward pressure against the backrest, rotate the backrest to align the actuator
extension tube with its corresponding mounting position and reinstall 3/8 hex bolts.
NOTE–
this step may require assistance to complete.
6
7
5
4
7
D
4
5
D
C
F
A
B
E
(not shown)
6
C
A
B
