Hex: 0.5"
Note Orientation
Reuse Original Part
s
Do Not Reuse
Do Not Remove
Hex: 0.25"
Torque to 6-8 Nm (8-11 lbf•ft)
1254
1253
1252
Fig. 2 -- Remove Control Spool
Fig. 3 -- Install Mounting Plate
Make sure prime mover (engine) is off.
Remove Old Control Spool (Fig. 2):
1. Note the position of the control handle and neutral
bracket. Control handle orientation should remain
the same after NSS installation.
2. Using a 7/16" or 3/8" wrench to remove the control
bracket hold down bolt. Slide the control spool/
handle assembly out of the unit.
3. Remove the control handle nut from the old control
spool with a 1/2 inch wrench.
4. Remove the old control spool from the control
handle, neutral bracket, and spring.
The control spool and its backup ring and O-ring
are the only parts that must be changed out. It is
not necessary to remove the control sleeve.
Install Mounting Plate (Fig. 3):
5. Install the mounting plate gasket (1252) and mount-
ing plate (1253), using the three 1/4-20 x 0.500 hex
head screws (1254) and torque to 6-8 Nm (8-11
lbf•ft).
Note: Be sure the gasket is correctly oriented and
does not block any mounting plate passages.
Control Spool Assembly (Fig. 4):
6. Place the backup ring (1209) and O-ring (303) on
the control spool assembly (1207) as shown (may
be preassembled).
7. Place the cam (1247) on the spool assembly and
install the 1/4 inch washer (1248) and 1/4–20 x 0.5
socket head screw (1249) into the cam locking
bracket (1246). Finger tighten and back off 1/4
turn.
0.40
1.25
1.8
9/16-18
UNF-2A Thd
30
0.182
Fig. 1 -- Special Alignment Tool
Procedure
The neutral start switch is designed to prevent the start
of the prime mover when the pump is not in neutral.
Sauer-Danfoss publication BLN-9939 (M46 Service
Manual) should be at hand as reference.
Figure 1 illustrates a special alignment tool to be used
in step 13. Dimensions are included for fabrication.
Piece parts should not be mixed from one kit to another due to possible incompatibility between kits
© Danfoss, 2013 BLN-10143 • Rev CA • September 2013 1
Service Kit Instructions
Series 40 - M46
Neutral start switch installation instructions
Note orientation
for reuse
1258
1251
Control Spool Assembly
1255
1256
1257
1236
Hex: 0.5"
Torque to 7-9 Nm
(10-23 lbf•ft)
Hex: 0.375"
Torque to 6-8 Nm
(8-11 lbf•ft)
Hex: 0.875"
Torque to 9-10 Nm
(12-14 lbf•ft)
A
(1249)
Note Orientation,
Re-install as Before
Internal Hex: 0.25"
Torque to 11-15 Nm
(8-11 lbf•ft)
Internal Hex: 0.25"
Do not torque
initially
1249
1248
1247
1250
1246
1207
1209
303
Lubricate
Lubricate
Fig. 4 -- Control Spool Assembly
Fig. 5 -- Control Handle Assembly
Fig. 6 -- Cover Assembly
8. Install O-ring (1250) on to the spool assembly.
9. Lubricate the O-rings, outside cam face, and corre-
sponding surface of the NSS cover with assembly
grease.
Control Handle Assembly (Fig. 5):
10. Fit the control handle and neutral bracket between
the ends of the spring.
Neutral Start Switch Cover Assembly (Fig. 6):
11. Place the control spool assembly in the neutral
start switch cover (1251). Put the spacer (1258)
over the spool.
12. Secure control handle assembly on the new spool
with the old nut. Torque to 7-9 Nm (10-12 lbf•ft).
Note: Make sure the control handle is in the correct
position for your application.
13. Visually align the notch in the cam (1247) with the
hole in the NSS cover (1251). Insert special align-
ment tool (Fig. 1) to hold the cam in position.
Finger tighten only.
14. Place neutral start cover gasket (1255) on the
mounting plate.
15. Place the neutral start cover assembly on to the
control sleeve and pump housing.
16. Attach the neutral start switch cover assembly on
the pump using the two 1/4–20 x 5/8 screws (1256)
and torque to 6-8 Nm (8-11 lbf•ft).
Note: It may be necessary to loosen and retorque
the bolts to prevent binding of the control handle.
Final Adjustments:
17. Set neutral on the control handle
using the proce-
dure outlined in BLN-9939, page 15.
18. Now torque the 1/4–20 x 0.500 socket head screw
(1249 - inside of view hole) to 11-15 Nm (8-11 lbf•ft).
19. Install the neutral start switch (1236) and torque to
9-10 Nm (12-14 lbf•ft).
20. Make certain neutral start switch continuity is bro-
ken before or at 50 psi differential system pressure.
Measure system pressure through system gauge
ports (see BLN-9939).
21. Install expansion plug (1257).
© Danfoss, 2013 BLN-10143 • Rev CA • September 2013 2
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