Technical Service Information Bulletin
Date: December 17, 2020
Bulletin Name: FDM-TSIB-018
Model: Oshkosh S-Series
Units Affected: MY 2020 and newer Front
Discharge Mixers

2.0 Steering Relief

Purpose:
This bulletin provides instruction to update the hydraulic steering system by adding an external pressure relief
valve. Field reports of failed steering pump seals led to testing that determined internal recirculation of hot oil was
the cause of the seal failures.

Notice:
• This bulletin should be read and understood in its entirety before performing this procedure.
• All procedures outlined in the bulletin must be performed by skilled service personnel. Refer to the product
service manual for descriptions of maintenance procedures.

SAFETY NOTICE

WARNING

Perform your company’s Lockout/Tagout
procedure. If your company does not have a
Lockout/Tagout procedure, follow OSHA
1910.147 and 1910.146 Confined Space as
appropriate.

Never remove hydraulic pipes/tubing, fittings,
and adapters until all pressure has been
relieved from the hydraulic system.

SAFETY NOTICE

All hydraulic pressures must be relieved from
the hydraulic system prior to removing any
components from the system to prevent oil
from spraying or functions and systems
from failing.

WARNING

Use appropriate Personal Protective
Equipment (PPE) as required by your
company.

WARNING

Hydraulic systems are hot. DO NOT TOUCH!
Serious personal injury may result from hot
oil. When you have completed working on the
hydraulic systems, thoroughly clean any
spilled oil from the equipment. Do not spill
any hydraulic fluids on the ground. Clean any
hydraulic fluids from your skin as soon as
you have completed your maintenance and
repairs. Dispose of used oil and filters as
required by law.

1

Tools and Equipment Required:
Customer to supply:
• Torque wrench (foot pounds)
• Hand Tools

Parts Required:
Item

Part Number

1

A000B931

FTG,ST 8JIC-8ORG FM ST SWVL

Description

Qty.
1

2

A000F499

FTG,T 8JIC-8ORG-8JIC MMM ST

1

3

A000B961

FTG,45 8JIC-8JIC MF ST SWVL

1

4

A000U233

MANF ASSY,HYD,HYD,STEERING

1

5

1144772

FTG,ST 8JIC-8ORG MM ST

1

6

1260477

FTG,T 10JIC-10JIC-10JIC MFM ST

1

7

A000U498

HOSE ASSY #8 CR 11.0 3125

1

8

A000E552

SEALANT,TORQUE INSPECTION,BLUE

A/R

Procedure:
Lockout/Tagout
1. Place unit on a flat surface, block truck tires, and perform your company’s Lockout/Tagout procedure. If your
company does not have a Lockout/Tagout procedure, follow OSHA 1910.147 and 1910.146 Confined Space as
appropriate.
2. The vehicle’s BATTERY DISCONNECT switch is located on the left-hand side of the battery box. Use the
battery disconnect switch when performing any maintenance so the vehicle cannot accidentally be started.
a. Turn the battery disconnect switch (Figure A, Item 1) counterclockwise so the hole on the switch aligns
with the hole in the bracket (Figure A, Item 2).
b. Install the safety lockout device ring (Figure B, Item 1) through the holes on the battery disconnect switch
and the bracket.
c. Install a padlock (Figure B, Item 2) onto the safety lockout device ring, lock it, and put the key in your
pocket. If more than one person is working on the vehicle, each person must install his or her own padlock.

2

1

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1

2

2

Figure A

Figure B

Steering Relief Installation
3. Disconnect the hydraulic supply line from 45° fitting on the main steering gear. See Figure 1.
4. Remove the 45° fitting from steering gear. The 45° fitting will not be reused. See Figure 1.

Hydraulic Supply
Line
45° Fitting

Figure 1

NOTE

Final tighten all components after alignment
of installed components is verified.
5. Install straight fitting (A000B931) into steering gear, see Figure 2. Final tighten to 45 ft. lbs.
6. Install T-fitting (A000F499) to straight fitting installed in Step 5. Orient T-fitting as shown in Figure 2.
7. Install 45° fitting (A000B961) to the bottom of T-fitting installed in Step 6. See Figure 2.
8. Connect the hydraulic supply line disconnected in Step 3 to the 45° fitting in bottom of the T-fitting.
See Figure 2.
9. Install relief valve assembly (A000U233) to the top of the T-fitting. Orient relief valve assembly as shown
in Figure 2.
10.
Apply torque sealant to valve assembly over adjustment screw so you can tell if the pressure relief setting
has been adjusted after installation.
11.

Install straight fitting (A000B889) to relief valve assembly. See Figure 2.

3

Relief Valve
Straight Fitting

Straight Fitting

T-Fitting
Hydraulic Supply
Line

45° Fitting

Figure 2

12.
Disconnect the main hydraulic return line from the existing t-fitting on the side of the hydraulic manifold.
See Figure 3.

Existing T-Fitting

Hydraulic Main
Return Line

Figure 3

4

13.

Install T-fitting (A000D112) to existing T-fitting. Orient T-fitting as shown in Figure 4.

14.

Connect hydraulic main return line to T-fitting installed in Step 13.

Existing T-Fitting
T-Fitting

Hydraulic Main
Return Line

Figure 4

15.

Connect the straight end of return line (A000U498) to relief valve straight fitting. See Figure 5.

16.

Connect the 90° end of return line to T-fitting installed in Step 13. See Figure 5.

T-Fitting

Straight Fitting

Return Line

Figure 5

5

17.

Make sure system components are aligned correctly and nothing is contacting the return line.

18.

Final torque all components. See Figure 6.

41 ft. lbs.
55 ft. lbs.

58 ft. lbs. 58 ft. lbs.

41 ft. lbs.
45 ft. lbs.

58 ft. lbs.

45 ft. lbs.

45 ft. lbs.

45 ft. lbs.

Figure 6

19.

Make sure the hydraulic reservoir is filled to the MAX mark.

20.

Reference bulletin FDM-TSIB-013 for bleeding air from the steering system.

21.

Remove lockout/tagout.

Continuous Improvement:

The change included in this document is part of the
McNeilus Continuous Improvement Process.
McNeilus’s quality policy is providing customer satisfaction
through innovative products, dedicated service, and a
constant focus on continuous improvement.
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