NHTSA ID Number: 10189433
Manufacturer Communication Number: MGM Catalogue
TSB/Document Date: 2021-03-29
Summary
MGM Brakes catalogue
Fastener Torque Value Chart........................................................................................................................................146
Procedure to Lengthen External Breather Tube...........................................................................................................147
Mixing Standard and Long Stroke Chambers...............................................................................................................148
Field Replacement of Chambers Equipped with “Welded” Yokes................................................................................149
Performance Chart - Spring Brake Chambers (including Remote Mount Cylinders) - SAE................................. 150-153
Performance Chart - Service Brake Chambers - SAE.......................................................................................... 154-155
Performance Chart - Spring Brake Chambers (including Remote Mount Cylinders) - METRIC.......................... 156-159
Performance Chart - Service Brake Chambers - METRIC................................................................................... 160-161
Note: Product information and specifications subject to change without notice.
137
TECHNICAL
Proper Brake Adjustment..............................................................................................................................................145
MJS SERVICE DIAPHRAGMS - REPLACEMENT
This bulletin is to notify customers of the availability of “reinforced” diaphragms for use in
MJS Model Chambers with spring brake parking force-output (pounds-force) in excess
of 2300 lbs. at 1¼-inches of stroke: i.e. MJSxx28 and xx30.
Due to the high force output provided by the power spring in MJSxx28 and xx30 Model
Chambers, the surface of the service diaphragm, where the “center-case” push rod and
diaphragm make contact, may chafe or wear affecting the long-term serviceability of the
diaphragm. In an effort to address this potential problem, MGM Engineering developed
type 20L3, 24L3, 30L3, and 36 “reinforced diaphragms with an extra layer of fabric
covering an area in the center of the diaphragm, approximately 1¾ -inches in diameter,
where the center push rod makes contact with the diaphragm.
TECHNICAL
MGM recommends using only MGM “reinforced” diaphragms for replacement in these
models. All diaphragms are available through the MGM Brakes PDC in both single-piece
packaged and 30-piece box bulk packs.
138
Note: Product information and specifications subject to change without notice.
HEXAVALENT CHROMIUM REPLACEMENT
1.0
PURPOSE:
To notify customers of coating conversion from current Yellow Zinc Dichromate (hexavalent chromium) to clear
trivalent chromate.
2.0
BACKGROUND:
Hexavalent chromium is used in surface coatings for corrosion protection in many vehicle components. On
February 28, 2006, the U.S. Department of Labor, Occupational Health and Safety Administration (OSHA) issued
final rule concerning Hexavalent chromium. The OSHA directive stated that Hexavalent chromium was
a carcinogen and set new limits for exposure to this hazardous material. The European Union’s directive 2000/53/
EC [1] known as the End of Life Vehicle Directive (ELVD) governs permissible use, reuse, recycling, and recovery
of end-of-life vehicles and their components. The objective of the ELVD is to encourage vehicle manufacturers to
limit the use of hazardous materials in their products. Hexavalent chromium is one of the materials controlled by
the ELVD, which calls for a total phasing out of hexavalent chromium coatings by July 2007.
SCOPE:
Hexavalent chromium is a key component of the yellow zinc dichromate plating used for corrosion protection
on clamp bands, clamp band bolts, continuous rings, and other hardware. MGM Brakes will be replacing the
yellow zinc dichromate coating on all components with a trivalent zinc chromate.
4.0
TIMELINE:
The new trivalent zinc chromate coating will be phased into production beginning in early 2007.
5.0
APPEARENCE:
The new coating will be clear or clear with a blue tint.
6.0
CORROSION PROTECTION:
The new coating will offer equal or greater salt spray protection when compared to yellow zinc dichromate.
YELLOW
YELLOW ZINC DICHROMATE
(HEXAVALENT CHROMIUM)
Note: Product information and specifications subject to change without notice.
SILVER
CLEAR TRIVALENT
CHROMATE
139
TECHNICAL
3.0
PRODUCT IDENTIFICATION PLATE
All MGM brake actuators made after October 1987 have an aluminum identification plate attached to the
actuator which contains the MGM Brakes part number, date code, and often a customer part number.
On all TR, LTR and MJ (Magnum Performance Plus) models the I.D. plate is attached to the center section
aluminum casting. On all C, CS and CW models the I.D. plate is attached to the pressure cap or to the
clamp band. See the illustrations below for I.D. plate locations.
MGM 3430051
M102710
XXXXXXXXXXX
TECHNICAL
Double Diaphragm
TR Model
Wedge
MJW Model
MGM Brakes Part Number
Date Code (month, day, year)
Customer Part Number (optional)
Long Life
Double Diaphragm
LTR Model
Remote Cylinder
140
Piston
Magnum Performance Plus Model
MJS Model
S-Cam Service
C and CS Models
Note: Product information and specifications subject to change without notice.
PRODUCT IDENTIFICATION PLATE
Introduction of Unit Serial Numbers
Starting March 2012, MGM Brakes introduced the serialization of brake chambers for improved identification
and traceability. This number is a randomly generated seven digit numeric number that is unique to each MGM
Brake model.
The serial number is located with the product identification (see illustration) that is either stamped directly on
the unit, or stamped on a tag that is affixed to the unit.
ALL CHARACTERS STAMPED
.120 X .005-.010 DEEP
CENTERED HORIZONTALLY
AND VERTICALLY ON PAD
MGM Brakes Part Number
Serial Number
Date Code
Customer Part Number (optional)
M 060512
Plant Code
M- Murphy OEM
R- Murphy OES & Aftermarket
C- Cloverdale OEM
V- Cloverdale OES & Aftermarket
Year
Day
Month
TECHNICAL
MGM 1234567890
123456
M033012
12345678901234
Date Code
Double Diaphragm
TR Model
Long Life
Double Diaphragm
LTR Model
Wedge
MJW Model
Note: Product information and specifications subject to change without notice.
Remote Cylinder
141
Piston
Magnum Performance Plus Model
MJS Model
S-Cam Service
C and CS Models
LONG STROKE IDENTIFICATION
“LONG STROKE”
SPRING BRAKE
IDENTIFICATION
STANDARDIZED TRAPEZOIDAL
SHAPED I.D. TAG SECURED TO
THE SERVICE SIDE CLAMP BAND
WITH BOLT AND PUSH NUT.
TECHNICAL
SQUARE PORTS ARE CAST
RIGHT INTO THE FLANGE CASE
TO ENSURE LONG STROKE
IDENTIFICATION THAT IS
PRONOUNCED AND EASILY
DETECTABLE.
SQUARE EMBOSSMENT IS
RAISED A FULL HALF-INCH FROM
THE TOP OF THE PRESSURE
CAP TO ENSURE LONG STROKE
IDENTIFICATION THAT IS
PRONOUNCED AND EASILY
DETECTABLE
142
Note: Product information and specifications subject to change without notice.
DOUBLE DIAPHRAGM TO PISTON CONVERSION CHART
1.0
PURPOSE:
The purpose of this technical bulletin is to recommend a MJ-ET piston type air brake actuator replacement for various
MG-T’s (now obsolete) and double diaphragm models.
CAUTION:
The recommended MJ-ET replacement may have more parking force than the model it is replacing. An anti
compounding valve may be required to prevent excess braking torque. Note: The J-Series (Magnum Performance
Plus) models listed on the chart below are 3.00 inch (76.2 mm) stroke actuators. Ensure that installations have
proper clearance for 3.00 inches (76.2 mm) of stroke.
MGM Brakes recommends replacing both brakes on an axle if force and/or stroke is different than unit being
replaced.
2.0
CROSS REFERENCE CHART:
The following chart provides an easy cross reference for selecting a MJ-ET piston type air brake actuator to replace a
MG-T (now obsolete) or double diaphragm air brake actuator.
3.0
MODEL NUMBER DEFINITIONS:
Model
Size
TR2430HD
2.50” (63.5 mm)
1580 lbs. (7.0 kN)
68 psi (4.7 bar)
TR3030HD
2.50” (63.5 mm)
1580 lbs. (7.0 kN)
68 psi (4.7 bar)
TR2430
3.00” (76.2 mm)
1435 lbs. (6.4 kN)
63 psi (4.3 bar)
TR2430HD
3.00” (76.2 mm)
1580 lbs. (7.0 kN)
68 psi (4.7 bar)
TR3030
3.00” (76.2 mm)
1435 lbs. (6.4 kN)
63 psi (4.3 bar)
TR3030HD
3.00” (76.2 mm)
1580 lbs. (7.0 kN)
68 psi (4.7 bar)
TR3036
2.50” (63.5 mm)
1960 lbs. (8.7 kN)
66 psi (4.6 bar)
TR3636
3.00” (76.2 mm)
1960 lbs. (8.7 kN)
68 psi (4.7 bar)
LTR2430
3.00” (76.2 mm)
1525 lbs. (6.8 kN)
71 psi (4.9 bar)
LTR3030
3.00” (76.2 mm)
1525 lbs. (6.8 kN)
71 psi (4.9 bar)
M1620LG-T
2.50” (63.5 mm)
1410 lbs. (6.3 kN)
50 psi (3.4 bar)
M1624LG-T
2.50” (63.5 mm)
1625 lbs. (7.2 kN)
56.8 psi (4.1 bar)
M2020LG-T
2.50” (63.5 mm)
1410 lbs. (6.3 kN)
50 psi (3.4 bar)
M2024LG-T
2.50” (63.5 mm)
1625 lbs. (7.2 kN)
59.6 psi (4.1 bar)
M2030LG-T
2.50” (63.5 mm)
2360 lbs. (10.5 kN)
58.2 psi (4.0 bar)
M2420LG-T
2.50” (63.5 mm)
1410 lbs. (6.3 kN)
50 psi (3.4 bar)
M2424LG-T
2.50” (63.5 mm)
1625 lbs. (7.2 kN)
59.3 psi (4.1 bar)
M2430LG-T
2.50” (63.5 mm)
2360 lbs. (10.5 kN)
68.2 psi (4.7 bar)
M3024GT
2.50” (63.5 mm)
1625 lbs (7.2 kN)
60 psi (4.1 bar)
M3027GT
2.50” (63.5 mm)
2040 lbs. (9.1 kN)
67 psi (4.6 bar)
M3031GT
2.50” (63.5 mm)
2325 lbs. (10.3 kN)
69 psi (4.8 bar)
lbs (kN)
Hold-Off
Pressure (A)
psi (bar)
MJS3630
MJS3030
MJS2430
MJS2030
MJS3628
MJS3028
MJS2428
MJS2028
MJS3024
MJS2424
MJS2024
MJS1724
MJS3022
MJS2422
1725 lbs (7.67 kN)
1922 lbs (8.5 kN)
2320 lbs (10.3 kN)
2450 lbs (10.9 kN)
63 psi (4.4 bar)
71 psi (4.9 bar)
73 psi (5.0 bar)
75psi (5.2 bar)
Note: Contact MGM Brakes Sales for models not specified above.
(A)
(B)
Hold-Off Pressure (psi) is measured as decreasing air pressure at .200” (of full “OFF” stroke position - (zero stroke)).
Parking Force (lbs. ± 10%) is measured at 1.25” (31.8 mm) of stroke.
Note: Product information and specifications subject to change without notice.
143
TECHNICAL
Parking
Force (B)
Stroke
Inches
(mm)
MJS2022
MJS1722
Model numbers for double diaphragm air brake actuators describe the diaphragm size. A model TR2430 describes
a type 24 service chamber diaphragm and a type 30 spring chamber diaphragm. Model numbers for piston type air
brake actuators describe the service chamber diaphragm size and a level of parking chamber force. A model
M2420LG-T describes a type 24 service chamber diaphragm and a parking chamber having 1410 lbs.
(6.3 kN) ± 10% force output at 1.25 inch (31.8 mm) stroke (see chart below).
PROCEDURE TO CUT A PUSH-ROD
PROCEDURE: TO CUT THE SERVICE PUSH-ROD TO PROPER LENGTH
!
Warning: Do not attempt to service or dissemble the spring chamber or any spring brake actuator.
A large spring in the spring chamber having extreme force could cause serious bodily injury if it
were suddenly released due to inadvertent removal of this clamp or tamper-resistant head.
IMPORTANT: Place blocks under wheels to prevent vehicle runaway before removing air brake actuators.
(a)
REMOVE WORN OR NON-FUNCTIONAL UNIT FROM VEHICLE. Determine manufacturer and model of unit to be replaced. Refer to
that manufacturer’s service manual for caging and removal instructions.
(b)
Make sure the spring chamber of the removed actuator is fully released (power spring caged) and the service brake push-rod is fully
retracted to zero stroke position (i.e. brake fully released). See chart below.
TECHNICAL
(c)
Model Series
Stroke
Measurement
TR 2.25
2.25” (57.2 mm)
3.6” (91.4 mm)
TR 2.50
2.50” (63.5 mm)
3.6” (91.4 mm)
TR 3.00
3.00” (76.2 mm)
3.6” (91.4 mm)
LTR 2.50
2.50” (63.5 mm)
2.20” (55.9 mm)
LTR 3.00
3.00” (76.2 mm)
2.80” (71.1 mm)
MJ 1.75
1.75” (44.5mm)
1.38” (35.1 mm)
MJ 3.00
3.00” (76.2 mm)
1.29” (32.8 mm)
NOTE: All measurements are from top of head to end of bolt TR, and top of the head
to the top of the release bolt head J-Series.
- Mixes well with conventional fluids
- Low-moisture formula provides excellent vapor lock...
- Ideal for hydraulic and disc brakes
- Provides an extra margin of safety in extreme braking...
- Mix of polyglycol ethers ensures hot brake-system operation...
- Excellent for ABS, disc and drum brake systems
- Delivers braking power when needed by avoiding a spongy...
- Both wet and dry boiling points exceed the minimum...
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TSB/Document ID: MGM Catalogue
Replacement Service Bulletin Number:
MFR Communication Date: 2017-12-05
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: SERVICE BRAKES, HYDRAULIC
MFR Component System:
MFR Component Subsystem:
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