Truck

Vehicle Axles

Introduction
The maximum permissible weights and dimensions of goods vehicles in the UK have traditionally been set out in the Road Vehicles (Construction and Use) Regulations 1986. The regulations specific to the maximum permissable weights (C&U) can be found under regulations 75, 77 and 79 of the act. However EU legislation in the form of directives have been incorporated into these regulations with EC directives setting common standards specific to International Transport (directive 85/3) and Domestic Transport operations (directive 96/53).

On 1 January 1999 directive 96/53 regarding weight limits was made law as part of the Road Vehicles (Authorised Weight) Regulations 1998 and was not included within the Construction and Use Regulations as a further amendment.

The Authorised Weight Regulations run in parallel with C&U regs, which results in operators opting to choose to comply with either set of regulations. However, you cannot comply with a combination of the two regulations.

Vehicle weights
The information laid out in the tables below show both Construction and Use (C&U) and Authorised Weight (AW) rules. However, please be aware, it is not possible to operate to the weight limits in the new regulations whilst using the axle spacings specified in the C&U regulations.

Vehicle Type Axle Weight (Kgs) Construction & Use Weight (Kgs) Authorised Weight
1. Rigid
- where distance between axles is at least 3 metres
- otherwise


2
2
3
4

 
17,000
16,260
25,000 (26,000 with RFS)
30,000 (32,000 with RFS)

 
18,000
(See - Weight by reference to axle spacing )
25,000 (26,000 with RFS)
30,000 (32,000 with RFS)
2. Drawbar Trailers
- where distance between axles is at least 3 metres
- otherwise


2
2
3
4


18,000
16,260
25,000
30,490


18,000
(See - Weight by reference to axle spacing )
24,000
24,000
3. Articulated Vehicles 3
4
5
6
25,000 (26,000 with RFS)
32,520 (35,000 with RFS)
38,000 (44,000**)
44,000**
26,000
36,000 (38,000*)
40,000
44,000***
4. Roadtrains
(Drawbar Combinations)
4
5
6
32,520 (35,000 with RFS)
32,520 (38,000 with RFS)
44,000**
36,000 (See - Weight by reference to axle spacing )
40,000 (The distance between the rear axle of the motor vehicle and the front axle of the trailer must not be less than 3 metres)
44,000*** (The distance between the rear axle of the motor vehicle and the front axle of the trailer must not be less than 3 metres)
RFS means that road friendly suspension is fitted on the drive axle. As an alternative each drive axle weight may not exceed 9,500kg (but see ** and *** below). Twin tyres must also be fitted.
* 38,000kg is permitted where the combination consists of a two axle tractor unit and a two axle semi-trailer, the weight of the tractor unit does not exceed 18,000kg, the weight of the semi- trailer does not exceed 20,000kg for which an axle spacing of at least 1.8m is required and drive axle is fitted with twin tyres and road friendly suspension.
** Operation over 38,000kg is restricted to certain road-rail movements, subject to conditions - see below.
*** Operation over 40,000kg requires the axle weight of each drive axle not to exceed 10,500kg, the drive axle(s) to have road friendly suspension OR not to exceed 8,500kg axle weight, the trailer to have road friendly suspension and each part of the vehicle combination to have three axles. (Operation over 41,000kg requires, in addition, the use of an engine complying with the Euro 2 standard (or better) or a gas engine.)

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44 tonnes operation
From March 1994 the construction and use regulations permitted six axle articulated and drawbar combinations to run at up to 44 tonnes. However, this is subject to conditions, on certain road-rail movements of which the following key points are applicable:

With effect from 1 January 1999, part of the EU weights rules (directive 96/53) was extended to cover five axled (3+2) articulated vehicles operating at 44 tonne operation. However, the provision is limited to a vehicle moving a 40ft ISO container to or from a railhead as part of an international rail-road movement, and only applies where the through international movement is by rail. It must be noted here, that in all cases the appropriate documents must be carried.

With the introduction of 44 tonne vehicle use having been permitted since 1 February 2001, in all instances, the vehicle being operated must comply with the requirements laid down in the table above.

Axle Weight Limits
The following table lays out the axle weight limts by Construction & Use and Authorised Weight limits.

Axle type Example Weight (Kg)
C&U
Weight (kg)
AW
1. One wheeled axle
a) fitted with a wide tyre (width of not less than 300mm)
or fitted with twin tyres at least 300mm apart
Wide Tyre 5,090  
b. otherwise Normal Tyre 4,600  
2. Two wheeled axle
a. Single tyred wheels
Axle 1 9,200 10,000
b. twin tyred or wide tyred Axle 2 10,170** 10,000
c. as above where the axle is the sole driving axle of a motor vehicle Axle 3 10,500** 11,500
3. Axle with more than two wheels in line transversely
- vehicles manufactured before 1 May 1983
1 of 2 closely spaced axles
or any 1 of 3 adjacent axles
  10,170  
Otherwise
- vehicle manufactured on or after 1 May 1983
  11,180
10,170
 
10,000
** Twin tyres must have the centres of their areas of contact with the road at least 300mm apart. Wide tyres must be at least 300mm wide.

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Bogie Weights - C&U

Two closely spaced axles (see Fig 1. and Fig 2. below)
The weight that two "closely spaced" axles (two axles spaced at least 1.02 metres but not more lhan 2.5 metres apart) on a motor vehicle, drawbar trailer or semi-trailer, may impose on the road depends on two factors:

The regulations provide a scale dependent on these distances and plated weights.

Fig 1. - Motor Vehicles
Vehicle Axle
Total maximum weight = 19,000kg provided every driving axle is fitted with twin tyres and either every driving axle has road friendly suspension (RFS) or neither of the axles has an axle weight exceeding 9,500kg.
Fig 2. - Trailers
Trailer Axle
Total maximum weight = 20,000kg.

Three closely-spaced axles (see Fig 3. and Fig 4. below)
Where three "closely spaced" axles are concerned, the weight that a motor vehicle, drawbar trailer or semi-trailer may impose upon the road surface will vary dependent upon the axle spacing between any adjoining axles. However this will apply only where;

When the distance of X or Y are both a minimum of 1.3 metres in spread, the axles may be plated at 7,500kg mgw (all or individually).
Fig 3.
Tri Axle
X or Y not less than 1.3 metres (adjoining axles)

Semi-trailer limits were amended on 1 January 1989, thus allowing each axle to be plated at 8,000kg. As a result of these amendments, the total weight of a tri-axle semi-trailer can be plated at 24,000kg, provided the following conditions are met:

(Tri-axle semi-trailers meeting these conditions)
Outer axle spread - maximum 3.25 metres.
Maximum plated weight for any axle = 8,000kg.
Maximum total weight = 24,000kg.
Fig 4.
Tri Axle
X or Y not less than 1.3 metres (adjoining axles)

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Bogie Weights - AW
As a result of the introduction of the Road Vehicles (Authorised Weight) Regulations 1998, requirements became simplified with changes taking effect from 1 January 1999.

Description of Axle Axle spacing Maximum Authorised Weight (Kg)
Driving tandem axle Less than 1 metre
Greater than or equal to 1 metre but less than 1.3 metres
Greater than or equal to 1.3 metres
Greater than or equal to 1.3 metres
11,500
16,000
18,000
19,000
Non-driving tandem axle Less than 1 metre
Greater than or equal to 1 metre but less than 1.3 metres
Greater than or equal to 1.3 metres but less than 1.8 metres
Greater than 1.8 metres
11,000
16,000
18,000
20,000
Description of axle Distance between any adjacent axles Maximum Authorised Weight (Kg)
Tri-axle Less than or equal to 1 metres
Greater than 1.3 metres
21,000
24,000

Weight by reference to axle spacing
There are many tables that detail the regulatory requirements within the C&U regs, in an effort to simplify matters, the DfT therefore introduced a simple calculation as shown in the table below.
By using this calculation, it is now straightforward to calculate the weight at which a vehicle will be allowed to operate under the authorised weight regulations. It must be noted however, that the factor will vary according to the number of axles, as follows:

NB. The calculated figure should be rounded up to the nearest 10kg if the resultant calculated number is less than the maximum authorised weight.

The maximum allowable weight in the UK is now the lower of the maximum authorised weight as defined in the regulations and that determined by applying the multiplier to the vehicle wheelbase. Therefore if the calculated figure is less than the maximum authorised weight in the UK then the vehicle is restricted to this lower figure. If this figure is greater than the maximum authorised weight in the UK, the vehicle may only operate at the maximum authorised weight in the UK. (See below)

Vehicle Factor
4 axle rigid
3 or more axle trailer which is not a semi-trailer or a centre axle trailer
5,000
3 axle rigid Articulated vehicle 5,500
2 axle rigid
All tractor units
2 axle trailer which is not a semi-trailer or a centre axle trailer
6,000

Examples
A two axle rigid motor vehicle with a 2.5 metre axle spread would be limited to 2.5 x 6,000 = 15,000kg. A four axle rigid motor vehicle with a 6.5 metre axle spread would be limited to 6.5 x 5,000 = 32,500kg which is above the maximum authorised weight. The maximum authorised weight of 32,000kg therefore applies.
An articulated vehicle with a distance of 7.28 metres between the kingpin and centre line of the rearmost axle would be limited to 7.28 x 5,500 = 40,040kg, therefore the maximum authorised weight of 40,000kg applies. However, if the vehicle is of five axle (3 + 2) configuration operating on an international road/rail movement and carrying a 40' ISO container (with all relevant documentation), then the vehicle can carry the full 40,040kg.

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