Stroke inch (mm)

Description

Page Number(s)

3425

TR2130LTH

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3426

TR2424LT

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3428

TR2430LT

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3431

TR3030T

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3432

TR3036T

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3450

TR2730TH

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3452

TR2736TH

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3623

TR2424LTHD

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3625

TR2430LTHD

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3627

TR2130LTHDH

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

3631

TR3030THD

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

TR2730THDH

2.50” (63.5 mm)

Air Disc/Spring/Service

88-89

MJB1722ET

3650

MJB1722ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB1724ET

MJB1724ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB2022ET

MJB2022ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB2024ET

MJB2024ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB2030ET

MJB2030ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB2124ET

MJB2124ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB2422ET

MJB2422ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB2424ET

MJB2424ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB2430ET

MJB2430ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB2730ET

MJB2730ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB3022ET

MJB3022ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

90-91

MJB3030ET

MJB3030ET

3.00” (76.2 mm)

Air Disc/Piston/Spring/Service

86-87

Obsolete

Replaced By

Note: For Transit / Special Applications (i.e. rod length, etc.,) refer to Section 10.

UNDERSTANDING MGM BRAKES PART NUMBERS

MGM Brakes assigns a 7-digit part number except Magnum Performance Plus (see below) to every assembly and part we manufacture.
This number code reveals information about the part.
EXPLANATION OF 7-DIGIT PART NUMBER

· 1st Two Digits Major models, groups, detail parts, kits, etc.
· 2nd Two Digits (a) Model size on major groups

(b) Detail parts identification all others
· 3rd Three Digits- Numerical sequence 001-999
(a) Spring brake singles – 001 through 050
Spring brake tandems – 051 through 999

(b) All others 001 through 999

1000000 – 1999999
2000000 – 2999999
3000000 – 3999999
4000000 – 4999999
5000000 – 5999999
8000000 – 8999999
8999999 – 9999999

EXAMPLE OF SYSTEM
Service Chamber
Wedge Spring Brake
Double Diaphragm Brake
Piston Type Brake
Remote Mount Cylinder
Parts/Assemblies/Valves
Kits

Example: MJS3030ET051

MAGNUM PERFORMANCE PLUS
NUMBERING SYSTEM
The Magnum “Performance” Plus
numbering system is uniquely different
from how MGM Brakes identified products
in the past. The Magnum Plus part number
contains all the information pertaining to
the brake, allowing anyone to identify not
only the model, but application, stroke,
features and serial number as well.

Model Series

Style

Service
Side

Spring
Side

Max.
Stroke

Feature

Serial
Number

MJ

S

30

30

E

T

051

Magnum
J-Series

S-Cam

Type 30

Type 30

3.00”
(76.2 mm)

Breather
Tube

Aftermarket
Complete
Assembly

NOTE: See chart Part Number / Model Designation on page 5 for more key model prefixes and suffixes.
Note: Product information and specifications subject to change without notice.

9

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UNDERSTANDING MGM BRAKES PART NUMBERS

P/N Series

SECTION 1
Standard Stroke
Model
Page(s)

Section 1: Double Diaphragm Spring Brakes.................................. 10-29

Industry Safety Reminder......................................................................................................................................... 13

Standard Stroke Models
TR

Tamper Resistant......................................................................................................................... 14-15

TR-HD

Tamper Resistant, Heavy-Duty.................................................................................................... 16-17

TR-T

Tamper Resistant, Tube............................................................................................................... 18-19

TR-THD

Tamper Resistant, Tube, Heavy-Duty.......................................................................................... 20-21

TR-THDW

Tamper Resistant, Tube, Heavy-Duty, Welded NPC................................................................... 22-23

TR-TS

Tamper Resistant, Tube, Severe Service.................................................................................... 24-25

TR-TSHD

Tamper Resistant, Tube, Severe Service, Heavy-Duty................................................................ 26-27

TR-TSHDW

Tamper Resistant, Tube, Severe Service, Heavy-Duty, Welded NPC......................................... 28-29

All type 30 Spring Side Brake Models include
“patent pending”

Corrosion Fighter Technology.
Note: Product information and specifications subject to change without notice.

11

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DOUBLE DIAPHRAGM - STANDARD STROKE

Corrosion Fighter Technology................................................................................................................................... 12

DOUBLE DIAPHRAGM - STANDARD STROKE

MODELS
Metal components of commercial vehicles are constantly
subjected to harsh corrosive environmental conditions,
particularly in the winter months in the northern climates. Until
recently, the coatings and materials used in spring brakes were
sufficient to effectively resist the corrosive effects of materials
found in the environments in which the vehicles operate,
including the effects of rock salt used to de-ice the roadways.
However, with the introduction of more aggressive deicing solutions, which literally “cling” to the surface, metal
components are experiencing much higher levels of corrosion.
In warmer weather, after the water has evaporated, the
corrosion process can be reactivated on rainy days when
moisture comes into contact with the crystallized salt deposits.

Composite guide

Note: guide is depicted in
orange for visual purposes.
Patents Pending.

Old guide

A way to reduce the effects of this “corrosive” attack is to break
the electrical conductivity between the parts by changing one
of the existing components to a non-conductive material.
This is what MGM Brakes Engineering has done by designing
a spring guide constructed from heavy-duty, non-conductive
composite material. The composite guide prevents metal to
metal contact between the end coil of the power spring and the
head of the brake, effectively “breaking the circuit”, therefore
slowing the corrosion process and reducing “corrosion” related
brake failures.
In addition to constructing the guide from composite material,
MGM Engineers made other design changes that significantly
improve power spring life by preventing damage to the power
spring’s protective coating. This was accomplished by enlarging
the area into which the power spring is compressed when the
parking brake is released. All this was done without increasing
the overall size of the brake.
Our spring guide also ensures precise alignment of the power
spring inside the brake. Accurate alignment of the head side
of the power spring compliments our patented Center-Hole
Diaphragm (CHD) design providing longer center seal and
power spring life.
MGM Spring Brakes are known for their durability and we are
proud that our products already utilize corrosion resistant
materials: such as A360 aluminum, epoxy coating and clear
trivalent chromate.

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Composite Guide - A Standard Feature
Constructed from heavy-duty, non-metallic composite
material. Available on all TR - type 30 spring side
model chambers. Patents Pending.

DANGER OF DOUBLE CLAMP BANDED SPRING BRAKES
Standard Stroke Model

INDUSTRY SAFETY REMINDER:

While removing the clamp band on the service side of a double diaphragm spring brake actuator carries little or no risk,
experience showed that all too often technicians did not follow the required safety procedures when removing the clamp band
on the spring parking side, resulting in a potential for severe personal injury. If the powerful spring in the spring parking side
is not properly “caged” before the clamp band is removed the spring can propel components of the assembly with great force,
potentially causing severe personal injury.
In response to this safety problem MGM Brakes pioneered the development in 1987 of the “Tamper Resistant” double diaphragm
spring brake actuator with the first “non-serviceable” spring parking side. By the early 1990’s the entire domestic industry
recognized the enhancement to safety offered by the “Tamper Resistant” design. Today every responsible spring brake
manufacturer based in the United States offers only spring brakes utilizing a “Tamper Resistant” technology. As a result of
the universal adoption of a “Tamper Resistant” design for the spring parking side of double diaphragm spring brake actuators,
instances of injury to workers from improper repair procedures or accidents have steadily declined until today they are virtually
nonexistent.
Unfortunately, a disturbing trend is emerging within the aftermarket portion of the heavy duty truck industry - the use of double
clamp banded spring brake actuators as replacements for damaged or failed “Tamper Resistant” units. This “reintroduction”
of double clamp banded spring brakes into the North American market seriously threatens worker safety in the heavy duty
truck industry. Especially at risk are those workers least experienced in the industry. Well over a decade has passed since
MGM Brakes’ introduction of “Tamper Resistant” spring parking brakes and many in the service and maintenance end of the
industry have not seen, let alone serviced, a double clamp banded spring brake. Younger workers are not likely to have been
trained in the special safety procedures required to cage the spring before servicing the spring parking side of double clamp
banded units.
Therefore, MGM Brakes believes the industry needs to be reminded of the dangers associated with servicing double clamp
banded spring brakes.
BE SURE TO PROPERLY “CAGE” THE SPRING IN THE SPRING PARKING SIDE ON ALL DOUBLE
DIAPHRAGM SPRING BRAKE ACTUATORS - EVEN “TAMPER RESISTANT” MODELS - BEFORE
ATTEMPTING ANY SERVICE ON THEM.
DO NOT ATTEMPT
TO REMOVE OR LOOSEN THE SPRING PARKING SIDE CLAMP BAND ON A DOUBLE

CLAMP BANDED SPRING BRAKE ACTUATOR UNDER ANY CIRCUMSTANCE.
IMPROPER SERVICING OF A DOUBLE CLAMP BANDED SPRING BRAKE ACTUATOR MAY RESULT IN
SEVERE PERSONAL INJURY DUE TO AN UNINTENTIONAL SEPARATION OF THE HEAD FROM THE BASE
OF THE UNIT.

Double Clamp Band
Spring Brake

MGM “TR”
Spring Brake

Spring Side
Clamp Band

Spring Side
No Clamp Band

Service Side
Clamp Band

Service Side
Clamp Band

Information taken from technical bulletin EB 06-003
Note: Product information and specifications subject to change without notice.

13

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DOUBLE DIAPHRAGM - STANDARD STROKE

Before 1989 double diaphragm spring brake actuators were manufactured using two clamp bands; one to seal the service side
and one to seal the spring parking side. At one time both sides of these units were considered “serviceable”, meaning that
if either side failed the clamp band could be removed, the diaphragm or other components could be replaced, and the unit
continued in service as repaired.

TR
Standard Stroke Model

Combination
D

Piggyback Plus Kit
VMRS# 013-004-000

VMRS# 013-004-001

DOUBLE DIAPHRAGM - STANDARD STROKE

B
A

X
E
C

F
G

• Tamper Resistant Design
• Molded Nitrile Rubber Push-Rod Air Seal
• Center Hole Shield
• Externally Stored Release Bolt
• Epoxy-Coated Head, Non-Pressure
Chamber and Lower Push-Rod Assembly
• 360 Aluminum Center Case
• “Long Life” Power Spring
• Epoxy Coated Return Spring
• Weatherseal™ Plug

TR Model Features

• Heavy-Duty Steel Non-Pressure Chamber
(8-Gauge Standard on Type 3030 & 3036 Aftermarket Models)
(6-Gauge Standard on Type 36 Models)
• Stroke Alert
• Polymer Push-Rod Guides
• Heavy-Duty Nylon Reinforced Diaphragms
• Heavy-Duty Nylon Reinforced Neoprene Diaphragms (Optional)
• Composite Guide - Corrision Fighter Technology (patent pending),
type 30 spring side models only