593-014

SB-10057157-7370
Field Service Bulletin
Trucks
Mack Trucks, Inc.
Greensboro, NC USA
Date
Group
No.
Release
Page
12.2014
593
014
01
1(9)
Grade Gripper Quick Release Valve,
Replacement
CHU, CXU, GU
FSB 593-014, Grade Gripper Quick Release Valve,
Replacement
(December 2014)
On some MACK CHU, CXU, and GU trucks built between 04/31/2008 and 01/05/2015, and
equipped with the grade gripper function may experience a slow release of the trailer’s
service brakes. Additionally, a delay in the release of the grade gripper function may be
caused by certain truck options and trailer combinations used by the operator. To prevent
further issues with the slow release of grade gripper, replace the existing DC-4 double check
valve (part number 25110484) with replacement QR-1 quick release valve (part number
20812943). Follow the replacement procedures outlined in this Field Service Bulletin (FSB).
Note: This bulletin does not apply to MACK Trucks Australia.
W5095214
Required Parts (Grade Gripper Quick Release Valve)
Item
Description
Part Number
Qty
1
Quick Release Valve
20812943
1
2
Plug, 11,7* 3/8 NPTF
3082875
1
3
Fitting, 9.5*1/2 NPTF
8397706
1
4
Fitting, 12.7*1/2 NPTF
8397707
1
5
Fitting, 12,7*3/8 NPTF (ESP-BAS1 Variant)
8397715
1
6
Fitting, 9.5*3/8 NPTF (UESP Variant)
8397714
1
7
Fitting
25091682
1
PV729-FSB593-014_M
USA67878
Mack Trucks, Inc.
Field Service Bulletin
Date
12.2014
Group
No.
Release
593
014
01
Note: Information is subject to change without notice.
Illustrations are used for reference only and can differ slightly from the actual vehicle being
serviced. However, key components addressed in this information are represented as
accurately as possible.
Procedure
You must read and understand the precautions and guidelines in Service Information,
Function Group 5, “General Safety Practices, Brakes and Air Systems” before performing
this procedure. If you are not properly trained and certified in this procedure, ask your
supervisor for training before you perform it.
1 Park the vehicle on a flat and level surface.
2 Apply the parking brake.
3 Place the transmission in neutral or park.
4 Install the wheel chocks.
W7086748
5 Disconnect the cable from the battery’s negative terminal.
W3086747
Page
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Mack Trucks, Inc.
Field Service Bulletin
Date
12.2014
Group
No.
Release
593
014
01
6 Drain the air system completely.
7 Using the proper air line removal tool, remove the air lines from the DC-4 double check
valve and tractor protection valve.
Note: Note the position of the air lines for installation purposes.
W5095215
8 Remove the fasteners and spacers securing the tractor protection valve and the trailer
electrical receptacle bracket to the truck cross member.
Note: Store the fasteners for reuse.
W5095216
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3(9)
Mack Trucks, Inc.
Field Service Bulletin
Date
12.2014
Group
No.
Release
593
014
01
9 Position the tractor protection valve to gain access to the DC-4 double check valve.
10 Remove the DC-4 double check valve from the tractor protection valve.
Note: Note the position of the existing valve and fittings for installation purposes.
Note: Discard the valve and fittings.
W5095220
11 Remove the union fitting (1) and tube fitting (2) from the tractor protection valve.
Note: Discard the fittings.
W5095222
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Mack Trucks, Inc.
Field Service Bulletin
Date
12.2014
Group
No.
Release
593
014
01
12 Apply thread sealant to union fitting (7) and install it onto the tractor protection valve.
13 Apply thread sealant to air brake fitting (5) or (6) and install it onto the tractor protection
valve.
Note: For appropriate selection of the air brake fitting, see the table below.
W5095226
Air Brake Fitting Selection
Item
Description
Part Number
Qty
5
Fitting, 12,7*3/8 NPTF (ESP-BAS1 Variant)
8397715
1
6
Fitting, 9.5*3/8 NPTF (UESP Variant)
8397714
1
14 Using thread sealant, install the fittings and plug onto the replacement QR-1 quick release
valve (part number 20812943).
W5095224
Page
5(9)
Mack Trucks, Inc.
Field Service Bulletin
Date
12.2014
Group
No.
Release
593
014
01
15 Using thread sealant, install the QR-1 quick release valve assembly onto the tractor
protection valve.
W5095227
16 Position the tractor protection valve and the trailer electrical receptacle bracket to the truck
cross member.
W5095228
Page
6(9)
Mack Trucks, Inc.
Field Service Bulletin
Date
12.2014
Group
No.
Release
593
014
01
17 Install the fasteners and spacers securing the valve assembly and bracket to the truck
cross member.
18 Tighten the fasteners to 12.5 ± 2.2 Nm (17 ± 3 ft-lb).
W5095229
19 Connect the previously removed air lines.
W5095230
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Mack Trucks, Inc.
Field Service Bulletin
Date
12.2014
Group
No.
Release
593
014
01
20 Connect the battery cable to the negative (ground) terminal.
W3086758
21 Start the truck, build up air pressure and check for air leaks during normal operation
pressure.
22 Remove the wheel chocks.
W7086759
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Mack Trucks, Inc.
Field Service Bulletin
Date
12.2014
Group
No.
Release
593
014
01
Reimbursement
This repair may be eligible for reimbursement
if a product failure was experienced within
time and mileage limits of the applicable
Warranty coverage. Reimbursement is
obtained via the normal claim handling
process.
UCHP
Reimbursement
eWarranty
Reimbursement
Claim Type (used only when uploading from
the Dealer Bus. Sys.)
01
01
Primary Labor Code (Grade Gripper Quick
Release Valve, Replacement)
5939-03-09-03
0.5 hrs.
F332F-01-80
0.5 hrs.
Causal Part
25110484
25110484
Labor Code
MACK Trucks North America reserves the right to make any changes in design or to make
additions to or upon its products without incurring any obligations to install the same on
vehicles previously built.
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