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Introduction of Trailer Brake Drums

Views:0     Author:Wondee Autoparts     Publish Time: 2021-11-25      Origin:Wondee Autoparts

A brake drum is the core component of vehicle braking system. Its function is to generate braking force and hinder vehicle movement or movement trend.


A brake drum is a matching part of internal tension shoe friction brakes. It should not only have the strength and stiffness, but also have as high and stable friction coefficient as possible, as well as appropriate wear resistance, heat resistance, heat dissipation and heat capacity.


Brake drums are widely used on axles of semi-trailers.


As shown in Figure 1 below. The brake drum is connected to the axle hub by tire bolts. When the vehicle is braking, the air brake system pushes the camshaft to rotate to spread out the brake shoes to apply pressure to the brake drums, so that the friction force between the brake pad and the brake drum generates braking torque, and finally stop the vehicle. The reliability of brake drums directly affects the driving safety of a vehicle.


Drum type brake system


Figure 1. Drum type brake system


A brake drum is one of the important parts of a trailer axle, It is mainly introduced from the following aspects:


1. Technical standards of brake drums


(1) The technical standard of brake drums shall comply with China national standard GB / T37336-2019.

(2) The technical standard of brake drum casting blanks shall comply with China national standard GB / T9439-2010.


2. Technical parameters of brake drums


As shown in Figure 2 below. Common technical parameters of brake drums are as follows:

Schematic diagram of brake drum parameters from a China’s manufacturer WONDEE Autoparts

Figure 2. Schematic diagram of brake drum parameters from a China's manufacturer WONDEE Autoparts


(1) A:(Overall Diameter of Drum)

(2) B:(Dust Shield Recess Diameter)

(3) C:(Brake Surface Diameter)

(4) D:(Overall Depth)

(5) E:(Brake Surface Flat)

(6) F:(Depth of Dust Shield Recess)

(7) G:(Squeeler Band Thickness)

(8) H:(Distance from Outside of Backface to Start of Taper)

(9) I:(Inside Finished Diameter)

(10) J:(Bolt Circle Diameter)

(11) K:(Pilot Diameter)

(12) L:(Outside Finished Diameter)

(13) M:(Diameter at Taper)

(14) N:(Backplate Thickness)

(15) O:(Bolt Holes: Number and Size)


3. Classification of brake drums


According to structure types of the brake drums, it can be divided into the following two types:


(1) Common brake drums


1) Single material brake drums


As shown in Figure 3 below. This kind of brake drums has the advantages of simple manufacturing process, stable performances and high cost performance. It is widely used in trucks, tractors, full trailers, agricultural vehicles and semi trailers.

Single material brake drums from a China’s manufacturer WONDEE Autoparts

Figure 3. Single material brake drums from a China's manufacturer WONDEE Autoparts


2) Bi-metal brake drums


As shown in Figure 4 below. As the name suggests, the braking part of the bi-metal brake drum is composed of two different metal layers inside and outside. The inner layer in contact with the friction lining is a cast iron part to ensure a good braking performance. The outer layer is made from high-strength steel to improve the strength and toughness of the brake drum. At present, this brake drum is currently in the trial stage in the market.

Bi-metal brake drums

Figure 4. Bi-metal brake drums from a China's manufacturer WONDEE Autoparts


(2) Brake hub-drums


As shown in Figure 5 below. A brake hub-drum combines the wheel hub and the brake drum into one. This drum is mostly used on light-duty trailers.

Brake hub-drums

Figure 5. Brake hub-drums from a China's manufacturer WONDEE Autoparts


4. Selection of brake drums


How to choose a brake drum in need correctly can be determined from the following aspects:


(1) Determine drums according to the OEM number of the automobile manufacturers, axle manufacturers or brake drum manufacturers.


As shown in Table 1 below, the OEM number of common trailer brake drums of well-known manufacturers.


Model

OEM number

Model

OEM number

Model

OEM number

MERCEDES BENZ

3014210501

BPW

310667290

MAN

81501100194

3014210701

310677040

81501100195

3014210901

310677590

81501100175

3014211301

310677670

81501100216

3014230001

310677630

81501100229

3014230101

310667120

81501100212

3014230301

310677720

81501100219

3014230801

310677940

81501100116

3014230901

310679060

81501100231

3524210401

310977720

81501100226

3524210501

310687150

81501100223

3544210001

310967050

81501100213

3544210101

BPW

327280140

Volvo

1134817

3544210301

327280860

1590313

3544210401

327280100

1075305

3604210601

327262200

1599678

3604210701

327262190

1599679

3604230101

327248460

1577439

3644210001

327248400

3171743

3814230001

327248780

3171744

FUWA  

3602.A

FUWA  

3601.A

3171745

3602.B

3601.B

3171746

3602.C

3601.C

3171747

3602.E

3601.E

3171748

3602.R

3601.R

SCANIA

1414153

3602.S

3601.S

1361331

3602.Q

3601.Q

1333117

3602.S1

3601.R1

1414152

3602.R1

3601.S1

1334075

3602.H

MITSUBISHI
  FOSO

MC807783

NISSAN

40203-90104

ISUZU

1-42315314-0

MC807781

43204-90545

1-42315336-0

MC828491

43204-90106

1-42315365-1

MC060504

43204-90071

1-42315377-1

MC838284

43204-90176

HINO

43512-2660

MC838283

43204-90215

43512-2830

MC865370

43204-90110

43512-2860

MC308941

FRUEHAUF
  TRAILOR
  TRAILER

AJA 595001

43512-3020

WEEB

66814F

AJA0489001

43512-3490

66816F

AJA0489002

43512-4011

66827B

AJA0490001

43512-4090

66852F

AJB0465001

ROR

21018963

66854F

AJB0465002

21018986

66864F/B

AJB0026001

21020038

66864B

AJB0335001

21021114

66865B

SAF

1064012800

21021114A

66873F

1064013000

21021164

61527B

1064014900

21223852

61528B

1064019700

Table 1. Common brake drum OEM numbers


(2) Determine drums according to brake drum drawings.


(3) Determine drums according to the basic sizes of a brake drum.


As shown in Figure 2 above, at least several parameters such as C, D, E, J, K, and O are required to determine the product.


5. How to measure a brake drum


As shown in Table 2 below. Relevant parameters of brake drums shall be measured as shown in the figure below.


1. Diameter of brake surface (C)

2.  Width of brake surface (E)

Brake drum measurement (8)

Brake drum measurement (1)

3. Overall  height of brake drum (D)

4. P.C.D.of bolt holes (J)

Brake drum measurement (4)

Brake drum measurement (5)

5. Diameter of bolt holes (O)

6. Diameter of center hole (K)

Brake drum measurement (2)

Brake drum measurement (6)

7. Outline characteristics of brake drum

8. Number of bolt holes

Brake drum measurement (7)

Brake drum measurement (3)

Table 2. Schematic diagram of brake drum measurement

6. Maintenance of brake drums


In order to achieve the longest service life and the best service performance of a brake drum, regular maintenance shall be carried out according to the maintenance manual of the vehicle manufacturer or axle manufacturer.


7. Replacement of brake drums


If one of the following problems occurs, the brake drum needs to be replaced. The brake drum must be replaced in pairs to ensure that both ends of a trailer axle have basically the same braking effect.


(1) The brake drum is cracked;

(2) Hot cracks, grooves or wear on the friction surface of the brake drum exceeds the limit of the brake drum;

(3) The mounting surface of the brake drum is cracked;

(4) The bolt hole of the brake drum is damaged;

(5) The brake drum is out-of-round.


8. Troubleshooting of brake drums


Troubleshooting table-problems, causes and troubleshooting methods are shown in Table 2 below:


No.

Problems

Pictures

Characteristics

Causes

Troubleshooting

1

Oversized Drums
  

01-Oversized DrumsIMG_256

The brake surface diameter is in excess of its specified maximum diameter.

The brake surface diameter is in excess of   its specified maximum diameter.

Replace the drum immediately.

2

Cracked Drums
  

02-Cracked DrumsIMG_257

A drum which has cracked completely through a section of the braking surface.

1. Excessive heating and cooling.
2. Excessive shoe pressure.
 
 

Replace the drum immediately.

3

Uniform excessive   wear

03-Uniform excessive wearIMG_258

The edge of the brake drum forms an extremely obvious step.

The brake drum is rapidly and evenly   worn due to heavy braking resistance, braking imbalance and the entry of dust   and impurities

Replace the brake drum in time.

4

Unilateral abnormal wear

04-Unilateral abnormal wearIMG_259

There are obvious wear marks on one side of the brake drum, but there are no obvious wear marks on the other side.

The Brake drum and brake lining are not concentric.

It is necessary to adjust the brake base   plate, brake support plate, brake shoe pin and other parts.

5

Heat Checking

IMG_25605-Heat Checking

A broken network of fine hairline cracks on  the braking surface of the drum, is a normal phenomenon of braking surfaces.

It is caused by regular heating and cooling of the surface.

Examine heat checks  frequently to make sure they have not grown deep  enough to weaken the drum.

6

Partial hot(black) spots

IMG_26206-Partial hot(black) spots

The spots neatly cover the entire friction surface of the brake drum,   forming a uniform parallel ring, or appear or form evenly distributed small round spots in a larger local area.

Uneven wear due to material and   structural errors of brake drum.

Replace the brake drum in time.

7

Martensite Spotted Drums

07-Martensite Spotted DrumsIMG_263

Martensite spotted drums have extremely hard, slightly raised, dark colored spots on the braking surface, shown uneven wear and the surface is out-of-round.

The spots are caused by very light brake applications with nonasbestos organic linings that are contacting the drum at a few  lining high spots.

Unless this is detected very early, the   brake drum should be Scrapped.

8

Brake drum grooves

08-Brake drum groovesIMG_264

Deep nicks or grooves are formed on the working surface of the inner circumference of the brake drum.

The wear of the brake lining exceeds the limit, causing sharp objects such as rivets to form pull grooves on the   working surface of the inner circumference of the brake drum.

Replace the brake drum and brake lining.

9

Scored Drums

IMG_26509-Scored Drums


Scored drums are signified by   circumferential grooves on the braking surface and excessive lining wear.

Replace the drum immediately.

10

Blue Drums

10-Blue DrumsIMG_267

A bluish disfiguration on the brake parts   (shoes, drums/rotors or bolts) indicates excessive heat.

This is usually caused by an oversized brake surface diameter/undersized rotor width or by weak or broken return springs.

Replace the drum immediately.

11

Brake drum backplate dropped

IMG_26811-Brake drum backplate dropped

The circumferential brake part   (cylinder) and flange part (disc) of the brake drum are separated

Improper structure and material during brake drum manufacturing.

Replace the brake drum in time.

12

Brake drum bolt holes are worn

IMG_26912-Brake drum bolt holes are worn

The bolt holes of the brake drum are abnormally worn, which are   elliptical holes.

The flange bolts (wheel bolts) are not fully tightened, and the brake  drum has relative movement impact with respect to the radial and axial   direction of the wheel hub.


Replace the brake drum in time.

13

Hub grease contamination


IMG_27013-Hub grease contamination

The lubricating oil / grease is thrown   onto the working surface of the inner circumference of the brake drum.

The hub oil seal fails, and the   lubricating oil / grease is thrown to the working surface of the inner   circumference of the brake drum.

Replace the brake drum in time.

14

Grease Stained Drums

14-Grease Stained DrumsIMG_271

Brake drums with discolored spots on the   braking surface, and oil or grease splattered on the brake assembly.

Over-lubrication of the cam or camshaft, or by an oil seal failure.

Replace the drum immediately.

15

Out-of-round drums
  

IMG_27215-Out-of-round drums

Variations in drum diameter at different points on the braking surface indicate out-of-round drums.

Variations in drum diameter at different points on the braking surface indicate out-of-round drums.

Replace the drum immediately.

Compiled by  WONDEE Autoparts

2021-11-25

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