Foton Series Light Bus. Instruction — part 14

OPERATION AND MAINTENANCE MANUAL FOR FOTON VIEW SERIES LIGHT BUS

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Sn

Description

Data

7

Lubricant volume (L)

0．4

8

Power assisted steering fluid

ATFⅢ automatic

transmission fluid

Q/SH038.501

9

Torque of track bar front end nut (N.m)

120.5±5

10

Tightening torque of cam nut (N.m)

200±8

11

Tightening torque of steering tie-rod locknut (N.m)

88±4

12

Tightening torque of ball joint of steering knuckle arm and tie-rod (N.m)

73．5~108

13

Maximum tangential force of steerer wheel

＜200

14

Driving deviation

When driving straight

along center line of test

track at 40km/h for

30m, the left

deviation<2m while the

right <1m (steering

wheel is released).

15

Minimum turning radius (m)

5．75

10.6.2 Structure Overview

Vehicle in driving needs to change direction (steering) often. Driver turns wheels (steered wheels) to an angle

with vehicle longitudinal axial line via steering axle (usually front axle). Beside, vehicle driving straight line are

often subjected to side interference on its steered wheels from road. The force makes steered wheels swinging to

change driving direction. Driver can turn steered wheel to reverse direction then, returning vehicle to its original

driving direction.

Steering system is composed mainly by steering operating mechanism, steering gear and steering driving

mechanism. Steering operating mechanism consists of steering wheel, steering spindle and steering column.

Steering gear changes steering wheel’s rotation into steering arm’s swing, and amplify steering operating force.

BJ6536 vehicle adopts ball rack and pinion steering gear with a ratio of 46.67. It has two stage driving sets: the

first stage is screw and nut driving sets, and second stage is rack and pinion driving sets. Steering mechanism

transmits output from steering gear to knuckle, turning wheels according to certain arrangement. The mechanism

consists of steering arm, drag link, tie rod and knuckle arm.

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Figure 10-6-1 Steering Column-1

1-Steering column assembly；2-Steering column seat assembly；3,4Bolt；5-Nut；6-Steering wheel assembly

Figure 10-6-2 Steering Column-2

1-1-Upper & inner shaft assembly; 2- circlip-Type A; 3-Bearing; 4-Rigid plastic flat gasket; 5-Spring; 6-washer;

7-Hexagon bolt and spring washer M16×8; 8-Upper Steering Column assembly; 9-Ignition switch lock; 10-Clips for upper

bracket; 11-Taper head bolt; 12-Intermediate steering column assembly; 13-Hexagon bolt, spring washer and flat washer set M8

×20; 14-Gimbal assembly; 15-Hexagon bolt, spring washer and flat washer M8×30-8.8; 16-Bolt M8×1.5×30; 17-Base for

steering column

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Figure 10-6-3 Steering Column-3

1-Steering drive shaft assembly; 2- snap ring; 3-Bearing; 4-Thrust ring; 5-Lower steering shaft compression spring; 6-Upper

column assembly; 7-Lower column assembly; 8-Upper bracket assembly; 9-Lower bracket assembly; 10-Cone bolt; 11-Nut; 12-Bolt;

13-Stud; 14-Universal joint assembly; 15-Steering base assembly; 16-Compression spring seat; 17-Return spring; 18-Tilt control

lever assembly; 19-Bolt; 20-Left ratchet stopper assembly; 21-Auxiliary tilt lever; 22-Left ratchet assembly; 23-Right ratchet

assembly; 24-Big washer; 25-Spring washer; 26-Hexagon nut; 27-Lever shaft; 28-Spring; 29-Tilt lever; 30-Right ratchet stopper

assembly; 31-Tension spring (2); 32-Protect panel of tilt lever; 33-Bolt shaft; 34-Split washer; 35-Tension spring (1); 36-Hexagon

flange nut; 37-Stud.

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Figure 10-6-4 Steering reducer

1-Steering reducer assembly; 2-Bolt M10×1.25×42; 3-Reducer support assembly; 4-Nut M10×1.25×8; 5-Bolt M10

×1.25×22; 6-Nut M10×1.25×25; 7-Nut M8×1.25×8; 8-Decelerator housing; 9-Dust coverⅡ; 10-Oil seal assembly;

11-Adjusting gasket/shim; 12-Bevel pinion; 13-Adjusting screw base; 14-Fixed yoke; 15-Hexagon bolt and spring washer M6

×12; 16-Bolt; 17-Bottom cover assembly; 18-Hexagonal nut type 1 -fine thread M8×1; 19-Adjusting screw; 20-Spring

seat; 21-Spring, Pull-out piece spring II; 22-Bigger bevel shifter; 23-Angular contact bearing 46103; Deep groove ball bearing

60202; 24-Spring stop; 25-Conical spring, Pull-out piece spring I; 26-Adjusting plug screw; 27-Lock nut; 28-Dust boot 1;

29- needle bearing 941/20; Deep groove ball bearing CHK182416; 30-Oil tight assembly, Oil tight/seal; 31-Double track needle

bearing, Deep groove ball bearing CHK182416

Figure 10-6-5 Steering Gear-1

1-Assembly of redirector with draw bar; 2-Left support bushing; 3-Bolt; 4-Left support assembly; 5-Right support

assembly; 6-Right support bushing; 7-Split Pin 3.2×22; 8-Nut; 9-Assembly for redirecting movable bushing B; 10-Bolt;

11-Down steering shaft assembly; 12-Bolt; 13-Assembly for redirecting movable jacket A; 14-Bolt; 15-Support sealing

assembly for steering drive axle jacket; 16-Left baffle for redirector B; 17-Bolt; 18-Right baffle for redirector; 19-Former

jacket; 20-Ormer protective clip

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Figure 10-6-6 Steering Gear-2 (Mechanical Steering Gear)

1-Rack pull-rod subassembly; 2-Rack lock plate; 3-Rack; 4-Joint support; 5-Nut; 6-Bar clasp; 7-Left protective

bushing; 8-Rack pull-rod subassembly; 9-Casing sleeve assembly; 10-Sleeve bushing; 11-Right jacket clip assembly;

12-Right protective jacket; 13-Angular contact bearing 46103; 14-Gear wheel; 15-Left jacket clip assembly; 16-Oil seal;

17-Locknut; 18-Jacket for oil seal of gear wheel; 19-Rack supporting base assembly; 20-O-shaped lock ring 45×2; 21-Spring

for supporting base; 22-Adjusting plug screw; 23-Locknut

Figure 10-6-7 Steering Gear-3 (Power Steering Gear)

1-Inner ball joint assembly; 2-Pull-rod lock sheet; 3-Rack piston assembly; 4-Oil sealing assembly φ46×φ28.2×8;

5-Bushing; 6-O-SHAPED RING 42.5 × 1.8; 7-Caging turnbuckle at end of cylinder; 8-Piston ring φ 46 × φ 42 × 2;
9-O-SHAPED RING 38.5×1.8; 10-Cone-shaped joint III; 11-Left oil tube assembly; 12-Right oil tube assembly; 13-Outer
ball joint assembly; 14-Hexagon nut -Grade C M15×1.5; 15-Bar clasp; 16-Protective case/Shield; 17-Clip assembly;
18-Gasket; 19-Oil cylinder casing assembly; 20-Tile-shaped parts for bracket; 21-Bracket; 22-Spring; 23-Spring cap;
24-Luck nut; 25-Bottom cover; 26-Oil sealing assembly φ38×φ27×7; 27-O-SHAPED RING 43.7×1.8; 28-Spool
assembly; 29-Oil sealing assembly; 30-Ball bearing; 31-O-SHAPED RING 53×1.8; 32-Coned-shaped joint I; 33-Valve
body; 34-Dust cover; 35-Hexagon bolt M8×25-6h; 36-Spring washer 8; 37-Coned-shaped Joint II; 38-Seal ring

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Figure 10-6-8 Power Steering cable

1-Steering cable assembly; 2-Bolt; 3-Oil pump washer; 4-Bolt; 5-Vacuum hose Ⅳ; 6-Joint; 7-Tee; 8-Vacuum hose

III; 9-Filter cleaner; 10-Bar clasp; 11-Vacuum hose Ⅰ; 12-Hoop; 13-Oil pipe; 14-Steering oil tank/can; 15-Bolt;

16-Steering oil pump; 17-Oil pump pulley; 18-Bolt; 19-V-shaped belt for vehicle; 20-Hoop; 21-Subassembly of bolts;

22-Support for oil pump; 23-Bolt; 24-Nut assembly 25-Bolt; 26-Idler wheel support; 27-Nut; 28-Bolt; 29-Idler wheel

belt support assembly; 30-Bolt; 31-Crankshaft belt pulley

10.6.3 Check, Maintenance and Repair

1. Check and repair – steering column tube supporter and steering shaft

(1) Check steering column tube supporter and steering shaft for bending and distortion. Correct if they are

bend, and shaft linearity error should not exceed 1.5mm.

(2) Replace parts if steering shaft spline is worn-out and spline has over two distort or damaged teeth.

(3) Replace steering bearing if it cannot rotate freely, and there is ball loss on inner/outer race or retaining

device is distorted.

2. Check and repair -- steering gear UJ and spline shaft/bush

(4) Steering gear cross shaft assembly

① Replace bearing if its needle is broken or needle number is insufficient.
② Replace cross shaft bearing if its fitting clearance with shaft journal exceeds 0.25mm, or it cannot

rotate freely.

③

Replace bearing if its sealing gasket or cover is failure.

④

Minor peel-off on cross shaft journal surface can be corrected by grinding. Replace it if there are

dent on journal surface and severe peel-offs, or shaft has crack on it or it is worn seriously.

(2) UJ fork spline, spline shaft and bush
① Replace part if UJ fork spline, spline shaft and bush are corroded seriously, or they have injuries or

cracks on them.

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② Replace spline shaft and bush if there are over two distort or damaged teeth.

3. Check and repair of steering gear assembly

Use pure light diesel, gasoline or cleaning fluid to wash the parts disassembled from the steering gear

thoroughly. Decrust the packing paper and dried sealant on steering gear connecting surfaces and side cover.

Check gear, rack, housing, rack pull rod and joint bracket for crack by using the methods such as oil impregnation,

knocking or magnetic particle checks. Replace if necessary. The oil seal and gasket are not reusable, replace with

new ones. If the protecting cover and O ring is aged, replace with new ones.

4. Maintenance of power steering system
① A new power steering gear needs change steering fluid after the vehicle has run for 2,500km. Meanwhile,

the filter in the reservoir should be washed. Since then change fluid and wash filter for every 50,000km or one

year.

② Monthly check the volume of fluid for fluid consumption, deterioration or excessive impurities. Replace

deteriorated fluid timely.

10.6.4 Typical Faults and Troubleshooting

1. Heavy steering wheel, see table 10-6-1.

Steering wheel is found heavy during driving. Jack up front axle, steering wheel still feels heavy after having

separated steering arm from drag link, the fault may come from steering mechanism due to over tighten moving

parts sets.

Table 10-6-1 Heavy steering wheel

Causes

Solutions

1. Bend steering spindle or over tighten bearing

1. Adjust or replace

2．Incorrect steering gear adjustment
①

Steering nut rack meshes too tightly with pinion

arm shaft

②

Excessive steering screw bearing pre-tension

2.Re-check and adjust

3. Damaged or stuck steering driving parts

① Worn out or damaged screw nut race and ball
② Damaged screw bearing retaining bracket

3. Repair or replace

4.Insufficient lubrication inside steering gear

4. Add gear fluid

2. Steered wheel oscillating and steering wheel shivering, see table 10-6-2.

Steered wheels oscillate and steering wheel shivers while vehicle is driving or during manufacturing and

assembling. These are due to that steered wheels keep swinging around kingpin.

Steered wheel oscillation has two types: self-simulated vibration and forced vibration.

Tyre deformed to sides creates self-stimulated vibration. Forces from road input eternal energy to steering

system during a vibration cycle. If energy input amount exceeds dumping energy inside steering system, the

system will increase its vibration to offset till balance is obtained. In this case, system keeps continuous vibration

in certain amplitude to create oscillation, its frequency is almost the same as system own frequency but different

from wheel rotation speed. This happens within a wider vehicle speed range. Usually, self-stimulated oscillation

happens at low speed.

In the event that steered wheels and steering system are under cycling stimulations, such as wheel

misalignment, excessive end face play, incorrect tyre geometrical/mechanical properties and motional interference,

they will form cycled interference as long as wheels are rolling. These continuous interferences create forced

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vibration. Once interference frequency matches system frequency, resonance is then created. Under resonance,

steered wheel oscillates with a frequency that is the same as that of wheel rotating speed, and usually comes with

obvious resonance speed, and its resonance range is narrow (3-5km/h). Oscillation happened at high vehicle speed

is usually of forced vibration type.

It is very complicated to pinpoint the cause and effect of steered wheel oscillation. It may be due to defects

during design and manufacturing such as wheel misalignment, incorrect wheel mechanical property, weak system

stiffness and damping, wrong steered wheel location angle and gyro effects. Mis-mounting and mis-adjustment

may be other causes, such as incorrect clearances among front axle steering system (it affects system stiffness) and

wrong friction coefficient (it affects damping) etc. There are many ways to restrain front wheel oscillation, such as

to select right parameters, make and assemble parts carefully. Other effective solutions include improving stiffness

of steering gear assembly/tie rod, vertical stiffness of suspension and tyre side stiffness, and adding transverse

shock absorber to increase damping ability etc.

Table 10-6-2 Steered wheel oscillating and steering wheel shivering

Causes

Solutions

1. Excessive fitting clearance between steering worm and nut,

or worn out

1. Readjust or replace

2. Loose or worn out steering bearing

2. Replace bearing

3. Excessive wheel dynamic unbalance

3. Perform dynamic balance check

4. Weak torsion bar spring

4. Replace

5. Incorrect front alignment angle

5. Adjust front wheel alignment angle

6. Failure shock absorber

6. Replace shock absorber

7. Distort vehicle frame (due to collision)

7. Adjust and repair

3. Insufficient steering wheel turns, see table 10-6-3.

While vehicle is driving, front wheel max turning angle becomes smaller (to RH or LH) while turning radius

becomes larger with poor steering sensitiveness. This is mainly due to incorrect adjustment and wrong mounting

location of parts such as steering gear, steering drive mechanism and front wheel turning angle-locating bolts.

Table 10-6-3 Insufficient steering wheel turns

Causes

Solutions

1. Incorrect steering screw rotation numbers

1. Remount and adjust

2. Parts in steering mechanism is distort due to force

2. Check and replace damaged parts

3. Mis-adjust front wheel turning angle locating bolt

3. Correct to right position according to specified

front angle

4. Excessive steering wheel turning number difference to

left and to right from center -- front wheel max turning

angle becomes small (to left or right)

4. While steering arm mounting angle is correct,

adjust front wheel turning angle locating bolt to

standard

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10.7 Suspension

10.7 Main Technical Parameters of Suspension

Main Technical Parameters of Suspension (with BJ491EQ1 Engine)

Sn

Description

Parameters

Type

Dual cross arm torsion bar type

independent suspension

Distance between locknut of track bar and fixing

bolt (mm)

445±3

Ground clearance (mm)

At front side 277mm; at rear side

305mm.

Torque of tire nut (N.m)

120~150

1

Front

suspension

Torque of front damper and lower cross arm (N.m)

88~97

Type

Rigid suspension of hydraulic type

shock absorber with vertical

arrangement semiellipse leaf

spring and bilateral action cylinder

Rear leaf spring section

Rectangle

First main leaf size (length x width x thickness)

(total number of leafs)

1200×60×8(5), flat spring eye

structure

Clamping center distance of U-bolt (mm)

90±0.5(Φ12)

Free static camber (to center of spring eye) (mm)

130

Tightening torque of U-bolt under flattening state

of the leaf spring (N.m)

123±5

Tightening torque of leaf spring pin (N.m)

147±5

Tightening torque of leaf spring shackle pin (N.m)

91±5

Torque of tire nut

120~150N.m

Top nut of rear shock absorber (N.m)

21.6~26.4

2

Rear

suspension

Toe nut of rear shock absorber (N.m)

38.7~47.3

Type

Bilateral action cylinder type

hydraulic shock absorber

Tightening torque of tightening nut of rear shock

absorber (N.m)

At top 21.6~26.4, at toe 38.7~47.3

Working stroke (mm)

205

Minimum length (when compressed through,

distance from the shackle center to top dust boot)

(mm)

320

＋3

-8

Maximum length (when pulled off, distance from

the shackle center to top dust boot ) (mm)

525

＋8

-3

Type of connection

Dual shackle

3

Shock

absorber

Designation of damping fluid

Q/SY11509-79 damper oil

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10.7.2 Structure Overview

If vehicle frame or body is directly mounted on axle, they will vibrate up and down on road. This will make

passenger uncomfortable or damage cargo. A suspension device must be adopted. The suspension refers to all

connecting devices between vehicle frame / body and axle, it is used to connect elastically axle to frame or body,

damping jerk to vehicle during driving to protect cargo and keep human comfort. The suspension reduces

vibration caused by spring system, transmits vertical, longitudinal and side counter force and moment of force; it

also guides wheel jump at certain trace corresponding to that of body.

Front suspension of BJ6536 series light bus is of independent type and its rear suspension is of rigid

semiellipse leaf spring vertical arrangement type.

See figure 10-7-1, figure 10-7-2, figure 10-7-3 for front and rear suspensions of BJ6536 series light bus.

Figure 10-7-1 Front Suspension Assembly-1

1-Left top across arm, shaft and pin assembly; 2-Right top across arm, shaft and pin assembly; 3-Top across arm shaft; 4-I

hexagon nut-small thread; 5-Small end cover; 6-Small outer collar, Small outer collar assembly; 7-Left top across arm seam;

8-Right top across arm seam; 9-Big outer collar, Big outer collar assembly; 10-Big end cover; 11-Nut; 12-Left top across arm

ball pin assembly, Right top across arm ball pin assembly; 13-Bolt; 14-Left bottom across arm assembly; 15-Right bottom

across arm assembly; 16-Rubber collar assembly; 17-Left bottom across arm seam; 18-Right bottom across arm seam;

19-Bottom buffer block assembly; 20-Metal lock nut with hexagon flange face, Spring washer; 21-Cam shaft assembly for

bottom across arm; 22-Bottom across arm cam shaft; 23-Spring washer; 24-I hexagon nut; 25-Bolt M10×1.25×31;

26-Heavy spring washer; 27-Heavy spring washer; 28-Heavy spring washer; 29-Nut M12×1.25; 30-Bolt M12×1.25×50;

31-Bolt M14×1.25×66; 32-Flat washer; 33-Hexagon-flange-faced bolt; 34-Top buffer block; 35-Left knuckle disc brake

assembly; 36-Right knuckle disc brake assembly

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Figure 10-7-2 Front Suspension Assembly-2

1-Bolt M12×1.25×98; 2-Torque bar seal assembly; 3-Metal lock nut with hexagon flange face; 4-Hexagon-flange-faced

bolt; 5-Torque bar dust cover; 6-Left torque bar; 7-Right torque bar; 8-Torque bar-rear bolt; 9-Top pad; 10-Left torque bar

fixing arm assembly; 11-Right torque bar fixing arm assembly; 12-Bottom pad; 13-Torque bar fixing bolt; 14-Torque bar

cover; 15-Hexagon bolt, spring washer and flat washer set; 16-Fixing plate for left stabilizer bar; 17-Fixing plate for right

stabilizer bar; 18-Stabilizer bar rubber collar; 19-Fix bracket for left stabilizer bar; 20-Fix bracket for right stabilizer bar;

21-Hexagon head bolt; 22-Hexagon head bolt; 23-Stabilized bar; 24-Bolt M10×1.25; 25-Stabilized bar pad; 26-Stabilized

bar rubber pad; 27-Stabilized bar connection shaft; 28-Stabilized bar pad (middle); 29-Thrust bar; 30-I hexogen nut-fine

thread; 31-Thrust bar pad; 32-Thrust bar rubber retainer ring; 33-Thrust bar rubber pad; 34-Thrust bar collar; 35-Undee

spring washer; 36-Hexagon head bolt; 37-Heavy spring washer; 38-Nut M12×1.25; 39-Front damper assembly; 40-I

hexogen nut –fine thread; 41-Bottom pad; 42-Top attachment assembly; 43-Front damper; 44-Spring washer 12;

45-Hexogen head bolt M12×1.25×55

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Figure 10-7-3 Rear Suspension Assembly

1-Rear stopper assembly; 2-Hexogen head bolt; 3-U bolt; 4-Rear steel plate spring assembly; 5-Steel plate spring pin;

6-Steel plate spring pin nut; 7-Rear plate splint assembly; 8-Flat washer; 9-U bolt nut; 10-Hexogen head bolt-fine thread;

11-Top pad for small hole; 12-Top ring for rear damper; 13-Top pad for big hole; 14-Rear damper assembly; 15-Bottom pad

for small hole; 16-Bottom ring for rear damper; 17-Bottom pad for big hole; 18-Lifting eye pin for plate spring; 19-Outer

plate for plate spring lifting eye; 20-Lifting eye pin collar for plate spring

10.7.3 Technical Specifications for Check and Repair

1. Repair of front suspension
① Check front suspension: compress and extend the shock absorber, check for abnormal resistance or

working sounds. If any, replace with a new shock absorber.

② Repair torsion bar spring: make fitting marks on torsion bar spring, torsion arm and fixed arm; measure

the length of extended bolt end A as shown in figure 10-7-4. The value of which will be a reference when

adjusting height of the vehicle; there are left and right index marks at rear end of torsion bar spring. Do not

install it to opposite direction.

Figure 10-7-4 Measurement of Length of Bolt A

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③ Mount and secure a new torsion bar spring onto the torsion arm, and adjust the nut seat and adjusting

nut. Note: When to install the fixed arm onto the torsion bar spring, tighten the adjusting nut by hand to make

the extended length of bolt being about 5mm, as shown in figure 10-7-5. Tighten the adjusting nut to screw down

the bolt by 60.5mm(C). The measured value of which will be a reference during vehicle height adjusting.

Figure 10-7-5 Installation of Torsion Bar Spring (1)

Figure 10-7-6 Installation of Torsion Bar Spring (2)

④ Check vehicle height. If the height is off standard, adjust it by using the adjusting nut of the torsion bar

spring.

⑤ Check front wheel alignment by wheel alinger.
⑥ When to install the stabilizer bar, tighten the nut until the extended length of the bolt reaches 4.5~6mm,

as shown in figure 10-7-7.

Figure 10-7-7 Installation of Stabilizer Bar

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2. Leaf Spring

(1) Check each leaf for crack, breaking and scratch; check center bolts and leaf clamps for distortion and

damage. Replace if necessary.

(2) Check each leaf’s laterally twisting. Measure by using center of leaf center hole as basis, the difference

to each end should not exceed 0.8% of leaf thickness.

(3) Measure leaf spring assembly performance after leafs have been clamped. The specifications for

front/rear/auxiliary leafs should be as indicated in chart 10-7-1. Replace part if arc height and stiffness of each leaf

change greatly (especially LH/RH changes) under static load.

(4) Leaf spring pin and bushing

Check front/rear leaf spring pins for uneven wear or damage by measuring their diameters. Replace parts if

wear exceeds limit. See table 10-7-2.

Table 10-7-1 Performance of Leaf Spring Assembly

Description

Free arc height (coil center)

Rear spring

156±6

Table 10-7-2 Service Limit of Rear Leaf spring Pin (mm)

Description

Standard

Limit

Rear leaf spring pin

φ14

φ13.8

Rear shackle pin

φ14

φ13.8

3. U-bolt

Check it for distortion, crack and damaged thread. Replace if necessary.

4. Leaf spring bracket and front shock absorber upper bracket.

Check and remount loose rivets. Check bracket for distortion. Repair bracket that has crack. And replace part

if necessary.

5. Front /rear leaf damper and auxiliary leaf bracket pad

Check them for damage, peeling or crack. Replace if necessary.

6. Rubber bushing of shock absorber shackle

Check shackle rubber bushing for aging, distortion and crack, replace if necessary.

10.7.5 Typical Faults and Troubleshooting

1. Broken or sounding leaf springs, see table 10-7-3.

Table 10-7-3 Broken or sounding leaf springs

Causes

Solutions

1. Boken leaf spring due to overload or driving on

rugged road

2. Loose U-bolt or worn-out pin/bush disturb wheel

alignment, or incorrect front/rear wheel base, which lead

to brake leaning and hard steering

3. Short lubrication — among leafs and on leaf pins

4. Elasticity diminishing varies among leafs, or certain

broken leaf make vehicle body slant.

5. Broken leaf or failure shock absorber, or damper lost

to disturb vehicle ride.

1. Load vehicle as specification, adjust vehicle

speed.

2. Fasten U-bolt as per specification while leafs

are pressed to flat, repair or replace worn-out

parts

3. Re-lubricate or replace parts

2. Check replace broken leaf or assembly

5. Replace broken leaf, shock absorber or damper

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2. Leaking or failure shock absorber, see table 10-7-4.

Table 10-7-4 Leaking or failure shock absorber

Causes

Solutions

1. Worn-out oil seal — shock absorber connecting rod

2. After long driving on rugged road, shock absorber

cylinder tube becomes hot

3. Failure shock absorber

4. Worn-out or lost absorber upper rubber bush,

absorber can not work normally

1. Repair or replace assembly

2. Remove to check shock absorber, replace if

it is failure

3. Replace

4. Replaced damaged parts

10.8. Brake System

10.8.2.1 Main Technical Parameters of Brake System

Main Technical Parameters of Brake System (with BJ491EQ1 engine)

Sn

Description

Data

1

Type of service brake system

Hydraulic operation dual-circuit brake system with

vacuum booster, front disc and rear drum brake

Front wheel

Disc brake

2

Brake

Rear wheel

Drum brake

Standard thickness

25

Service limit

22.5

3

Brake disc (mm)

Lateral run-out

tolerance

0．07~0．12

Standard thickness

10

4

Front friction lining (mm)

Service limit

1．6

Nominal values

φ270

Service limit

φ272

Taper

0．15

5

Inner diameter of brake

drum (mm)

Out of round

0．15

Standard thickness

5．5

6

Rear wheel friction lining

(mm)

Minimum service

thickness

1．0

Diameter

φ25.41

7

Dimension of brake master

cylinder (mm)

Stroke

30

8

Rear wheel cylinder diameter (mm)

φ23.81

9

Brake fluid

V-3QC/T670

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Sn

Description

Data

10

Type of parking brake system

Mechanical operation, rear wheel brake

supplemented with the parking brake

11

Brake pedal height (mm)

151.5±2

12

Free travel of brake pedal (mm)

1~3

13

Margin distance of pedal travel (pedal travel

from the ground) (mm)

58

14

Fit clearance between brake drum and brake

shoe (mm)

0.6

15

Road test the braking distance ( at 30km/h on

cement road surface) (no part of the vehicle is

allowed to be beyond the test track by 2.5m).

Braking distance≤8m; error≤60mm

16

Requirements for parking brake

Parking brake unit creates required braking

performance when it operates within 2/3 travel of

operating devices

10.8.2 Structure Overview

I. Brief Introduction of the Structure

The device sets used to force vehicle to stop by applying force from road on wheels are called brake system.

It is used to force vehicle to decelerate and stop, or park a vehicle firmly on various road conditions (including on

hill), and keep stable vehicle speed at driving down hill. BJ6536 light bus adopts two independent brake systems:

service brake system used on FR/RR wheels (dual hydraulic circuits with vaccum booster) and parking system

used on transmission mechanism.

Service brake system consists of wheel brake and hydraulic driving mechanism, and is operated by human

foot. Parking brake system consists of central drum brake and parking brake transmission mechanism, used at

parking or starting up on uphill, is operated by hand. In emergency braking situation, parking brake system and

driving brake system are used at the same time. In the event service brake system is faulty during vehicle driving,

driver should move vehicle by using parking brake system to a safe place or service station for check and repair.

Front disc brake is shown in figure 10-8-1.