The Self-propelled modular transporter simply referred to as SPMT is a platform vehicle with a large array of wheels that is used to transport massive objects.

It is primarily applied in the transportation of project cargo, constructions and movement of petrochemical components, etc.

Quite often, especially during load-outs, they are used to drive heavy components onto the barge from the seafront. 

  • Technical Description

The SPMT comes with a Power Pack Unit (PPU) and axle line modular unit.

The modular unit has a hydraulic suspension, which is available in three types: wheel bogies-drive, wheel bogies-idle and wheel bogies-braked.

The transporter can attain 3 or 4 hydraulic points offering support through the operation of the ball valves making it possible to divide the modular unit into groups.

The lifting compensation in this design is ±350mm. The modular unit also adopts seven electronic multi-modes steering modes:

diagonal wheel steering along mode, all wheel steering along mode, all wheel steering cross mode, front wheel steering mode, rear wheel steering mode, circle steering mode, diagonal wheel steering cross mode and the circle steering mode.

The maximum angle of steering is ±106º. Wheel bogie steering of this transporter is actualized through a rack and pinion gear steering device.

The hydraulic brake cylinder, as well as the hydraulic braking system, provides a braking force of 80 KN per brake axle line.

It is also equipped with an electronic propelled anti-skid system that can also use CAN (Control Area Network) bus system, allowing the micro-controllers and other devices in it to communicate with each other during operations.

Again, SPMTs have a radio remote controller where all the control functions of the transporters are integrated to actualize the general control and operation of the transporter.

Loading on the SPMT is taken by the frame structure and the suspension system constructed of a high strength material (690 MPa).

There are also hydraulic coupling pins that are normally used between the modular unit and the PPU and again between modular units in an end-by-end connection.

The coupling efficiency is significantly high due to the fast coupling of the hydraulic pipe and the electric connectors of the electric cable.

Now, we provide two broad classifications of the SPMT: the 3m width SPMT and 2.43m width SPMT, their specs are as follows:


One. 3m SPMT

The 3m SPMT is a self-propelled modular transporter with a width of 3 meters.

Its primary use is in the transportation of heavy loads such as prefabricated steel sections, complete sections and an entire ship in the shipyard as well as in other offshore workplaces.

The transporter can drive under the cradle bearing the heavy loads, lift the heavy loads through the use of the hydraulic lifting system, move the heavy loads to the desired destinations and comfortably offload them via the hydraulic lifting system again.

Throughout the process, no hoisting equipment or crane is needed. Most important to note is the fact that the transporter can comfortably and safely be controlled and operated by one person. Here are the vehicle entity components attached to it:


1.1 3m SPMT Technical Description

The gross load of each of the axle line is 40 tons, payload is 36 tons / axle-line. Here are the parameters of 3m SPMT modular unit:

3m width 6 axles spmt

3m width 6 axles spmt

3m width 6 axles spmt specs

3m width 6 axles spmt specs


3m width 4 axles spmt

3m width 4 axles spmt

3m width 4 axles spmt specs

3m width 4 axles spmt specs


1.2 3m SPMT Technical Parameters of PPU

There are two types of 3m SPMT with different PPU units. These include the:

  • 3m width PPU (350kw) and 3m width PPU (155kw)
3m spmt ppu specs

3m spmt ppu specs


Two. 2.43m SPMT

The 2.43m SPMT is a self-propelled modular transporter, which has a width of 2.43 meters. Similar to the 3m SPMT. It can be transported through a flat rack container.

2.1 2.43m SPMT Technical Description

Based on axle-line configuration and weight per axle-line capacity, there are 4 different types of the 2.43m SPMT. These are the:

  • 2.43m width 4 axle-lines modular unit (40t / axle-line capacity)
  • 2.43m width 6 axle-lines modular unit (40t / axle-line capacity)
  • 2.43m width 4 axle-lines modular unit (48t / axle-line capacity)
  • 2.43m width 6 axle-lines modular unit (48t / axle-line capacity)
6 axles spmt

2.43m width 6 axle-lines modular unit (48t / axle-line capacity)

2.43m 6 axles SPMT 40T

2.43m width 6 axle-lines modular unit (40t / axle-line capacity)

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Here is a diagrammatic representation of the:

4 axles spmt

2.43m width 4 axle-lines modular unit

spmt drawing

2.43m width 4 axle-lines modular unit


2.2 The Technical Parameters of 2.43m SPMT PPU

The 2.43m SPMT are of two types as well based on the PPU. These are:

  • 2.43m width PPU (350kw) and 2.43m width PPU (155kw)
Spmt PPU specs

2.43m SPMT PPU (350kw) specs

2.43m spmt PPU

2.43m SPMT PPU (155kw) specs

Here are the drawing of 2.43m SPMT PPU:

ppu spmt

2.43m SPMT PPU (350kw)

2.43m SPMT PPU 155kw

2.43m SPMT PPU (155kw)

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Three. Specs of the SPMT

3.1 Loading Capacity

The SPMT platforms are resistant to bending and torsion and are perfectly designed for direct loading. The design and the hydraulics are meant to take up to between 40 and 48 tons for each of the axle lines.

With SPMTs, there is a possibility of having a circle drive at the centre or the possibility of having lateral moves. 

3.2 Different Wheel Bogies

SPMT are available in two axial-configuration types: 4 axle-type and 6 axle-type. The axles are of three different types: wheel bogies-driven, wheel bogies-braked and wheel bogies-idle.

Bogies-braked: In this type, axles are ever in braked position during movement. Un-braking is done before getting powered via a power pack unit.

Bogies-idle: Here, the axles are ever in a free position. The braking and acceleration operations are controlled separately through the power pack unit.

Bogies-driven:  In this configuration, the Axles of the transporter are powered by a power pack unit for them to start functioning.

wheel bogies

Different wheel bogies

The entire hydraulic suspension system comprises a bogie frame, hydraulic suspension cylinder, rocker arm, the axle with or without brake or with drive, tyre and so on.

Still, there are hydraulic suspension cylinders in between the rocker arm and the bogie frame for use in providing bearing and connection to the load with an adjustment of ±350mm of the hydraulic suspension.

The reducer and the motor installed on wheel bogies with drive offer driving force for the vehicle.

The bogies with brake option have the axle installed with a brake that has brake cylinder on it used for achieving the service brake and providing the parking brake for the vehicle.

Each of the three-wheel bogies types is all provided with a mechanical stopper to control the max position and the use of the suspension cylinder minimum stroke to aid in controlling the lowest position.

There is a pin used for locking the suspension cylinder’s lowest position needed when doing vehicle transportation, axle repair and tyre replacement.

3.3 Stability of SPMTs

Each transporter can form 3 to 4 points supporting. Each of the different fields can keep hydraulic pressure to each of the axles in the given fields.

This makes it possible for the transporter to make desired adjustments when travelling through uneven surfaces enhancing the load stability.

Wide wheel track and low loading height ensure good stability for operations. Here are important hydraulic parts and systems enhancing stability in SPMTs:

spmt support

spmt support

3.4 Hydraulic System

  • Hydrostatic Drive System

This is a closed-loop hydraulic system that comprises the drive pump and a variable pump where the variable control is electric proportional (EP) control. Its primary function is to drive the transporter through the hydraulic controls.

  • Hydraulic Steering System

This is an open-loop system. An open-loop variable pump is used to integrate the load-sensing and pressure-cutting-off flow control operation.

The variable pump output flow can be adjusted based on the need necessitated by the load in order to save on the energy.

The use of the pressure-cutting-off flow control operation helps in restricting the max output pressure of the variable pump.

  • Hydraulic Lifting System

The hydraulic lifting systems, as well as the hydraulic steering system, have a common open-loop variable pump.

The hydraulic oil proceeding from the pump gets supplied directly to the lifting cylinder uniformly to ensure an even lifting of the platform.

  • Hydraulic Brake System

The braking and release of the modular transporters’ parking brake are realized through the hydraulic brake cylinder when it gets to push and release the brake drum.

The cylinder has springs inside it that can keep the trailer in the position of the parking brake when there isn’t any pressure oil contained in the cylinder.

The manual pump is installed with the braking system and is used for releasing the parking brake when the vehicle has no power.

3.5 Power of PPU

The PPU comprises a diesel engine, transfer case, radiator, hydraulic oil cooler, air filter, fuel tank, variable pump, hydraulic oil tank intercooler, micro-control system and the storage battery and so on.

The PPU can be lifted through the lifting cylinder of the unit to a height similar to that of the platform can as well be lifted up 12°to adapt to the nature of a road’s slope.

The PPU is responsible for the supply of power to all hydraulic systems supporting the control of the axle height, braking, and the powering of electrical systems and for steering as well.

The PPU supplies pressure oil needed for the hydrostatically driven transporter for used in steering, driving and lift operations.

3.6 Frame

The frame platform is typically the main component that bears the load.

Other important parts working together in bearing the load with the frame are the modular unit comprising the wheel bogie,

the main girder among others that adopt a strong box-type beam structure of a high-performance welding plate construction of yield strength of 690MPa.

The entire frame is strong with an ability to withstand bending and for efficiently handling concentrated loading.

Additionally, there are 3-chips-shape pin holes in the middle section of both ends of the frame meant for use in the end-by-end coupling.

There are also bolt holes on either side of the frame used for coupling side-by-side. It also has 4-hook points adjacent to the frame corners used for bearing the dead weight of the entire modular unit during hoisting operations.

axles modular transporter

spmt frame

Getting to the Tyre Replacement and /Or Offloading Position

  • lift down the entire trailer to the lowest position
  • insert the locking pin in the wheel bogie where the replacement needs to be done
  • shut off the suspension cylinder’s ball valve
  • lift the entire transporter up and make the replacement
  • lift down the entire trailer to the lowest position following the replacement
  • remove the locking pin and open the suspension cylinder’s ball valve
  • lift up the entire trailer to the driving height

The pneumatic tyre used is 355/65-15, which is desirable for satisfying the requirements of taking up the entire vehicle which is 1.1 times that of dynamic loads.

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The Self-Propelled Modular Transporter is a very useful vehicle in the transportation of heavy components and parts, especially in a shipyard.

The transporter is adapted to function in various ways based on the amount of load to be taken and the nature of the transportation surface.

For a bigger size of the load, the 3m SPMT can be used whereas the 2.43m can be used for relatively smaller applications.

Other considerations to be made are the power rating for each of the engine diesel for the PPU.

Different elements are meant for different applications hence the need to look into all these details to make a choice that will feasibly fit in for your use.

Read More:

Difference Between SPMT (Self-Propelled Modular Transporter) and Modular Trailer

How to Replace a Bridge in Only 22 Minutes By SPMT (Self-propelled modular transporter)

How China SPMT Ensure Quality? Find Your Best Manufacturer & Producer

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