Scania Leaf spring suspension. Manual - part 2

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Front springs and spring brackets

Between the spring assembly and the front axle 
is a wedge-shaped bracket that determines the 
angle of inclination of the front axle, i.e. the 
caster angle, and acts as a bracket for the anti-
roll bar. Re-adjusting can be carried out using 
adjusting wedges of 0.5-4°.

1

Adjusting wedge

2

Bracket 

Front axle

1

Adjusting wedge

2

Wedge-shaped spacer

Front axle2

Vehicles with double front axles do not have an 
anti-roll bar fitted to the rear front axle. Between 
the springs and front axle 2 is a wedge-shaped 
spacer and, if used, adjusting wedges.

Front springs and spring brackets

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Rear springs and wedge-shaped 
spacers

In some cases, wedge-shaped spacers are also used 
at the rear springs, to adapt the angle of inclination 
of the rear axle.

For this purpose, wedge-shaped spacers are 
available in different angles.

A spacer is chosen that gives the rear axle a 
suitable angle of inclination, taking into account 
the angles of the propeller shaft universal joints.

Rear springs with helper springs

On trucks with one rear axle and multi-leaf 
springs, the rear suspension consists of a main 
spring and a helper spring. The main spring is 
attached to the frame using a spring bolt and a 
spring bracket at the front end, and using a spring 
bolt and a movable spring shackle at the rear end.

On top of the main spring is the helper spring, 
which is not fixed to the frame.

The helper spring on the multi-leaf spring is a 
separate spring assembly. On parabolic springs, the 
helper spring is assembled together with the main 
spring, using the centre bolt.

When the truck is laden, the main spring is placed 
under load. The ends of the helper springs make 
contact with the two curved brackets that are 
riveted to the frame. If the load on the vehicle is 
increased further, the ends of the helper springs 
"roll" against the brackets, causing a reduction in 
the effective length of the helper spring, and the 
spring becomes stiffer.

Main spring with helper spring

Rear springs

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Rear springs with tag axle

On trucks with tag axle, the springs are located 
under the driving axle.

The front ends of the springs are attached to the 
spring brackets using spring bolts. The rear ends of 
the springs are attached to balance arms using 
spring shackles.

When under load, the driving axle will attempt to 
lift from the springs. This places large demands on 
the joint between the driving axle and the springs.

Suspension on trucks with tag axle

Suspension movement

The tag axle wheels are suspended separately on 
balance arms that are mounted in a shaft on the 
frame. The front arm of the balance arm is 
connected by a link to the rear end of the driving 
axle spring.

This method of suspension means that both the 
driving wheels and the tag axle wheels can follow 
the contours in the road. The weight distribution 
between the driving axle and the tag axle is more 
or less unchanged when the suspension is in 
action.

Rear springs with tag axle

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Rear springs for tandem bogie

Trucks with a tandem driven bogie are either 
equipped with balance tandem or with four-spring 
tandem. These are equipped with multi-leaf or 
parabolic springs, depending on the type of 
vehicle. The axles are held in place using torque 
rods.

Balance tandem

Balance tandem

The balance tandem has one spring on each side of 
the frame. The springs are attached in the middle 
using spring bearings which can turn, and which 
are mounted in a frame bracket. The ends of the 
springs rest against each rear axle. When under 
load, the springs attempt to lift from the sliding 
surface on the bracket. This places large demands 
on the joint between the driving axle and the 
springs.

Four-spring tandem

In some markets, a four-spring tandem may be 
fitted.

The four-spring tandem has two springs on each 
side. The axles are held in place using torque rods. 
The springs rest against their sliding surfaces on 
the frame bracket. Between the springs is a link 
that evens out the loads between the front and rear 
axle during suspension action.

Four-spring tandem

Rear springs for tandem bogie