Cranes on Trailers

We are the leader for installing cranes on trailers with applications across many sectors including rail, recovery, industrial pumps and logging.

It can be a great idea to fit a crane to a trailer as it leaves the towing vehicle free to carry its full payload, especially if a crane is not always required. There are, however, some key points that must be addressed for any trailer mounted crane to be a success. Penny Engineering never lets a trailer fitted with a crane leave its yard until it has been stability tested, weighed, hitch height checked, and nose weight taken to make sure that it is all safe and within the trailer and tow vehicle’s specified parameters.

Trailers are not designed to have cranes fitted to them and they offer little stability as they have little self-weight compared to a vehicle. Think carefully about what you need the crane to do and choose the smallest crane that will do the job. We then need to make sure that it will be safe both when in use and when being towed.

Trailer Cranes: A comprehensive guide to cranes on trailers. – Trailer Cranes – Penny Engineering
Trailer Cranes – Draft – Trailer Cranes – Penny Engineering

Your Trailer

Once you know what you need to carry you can think about which trailer to buy. Always include the weight of the crane and mounting frame as well as your required payload in any calculation of carrying capacity. A crane system can weigh anywhere between 100kgs for a 250kgs SwingLift to 750kgs for a 2.0 tonne PH all hydraulic unit.

Pay particular attention to the maximum permissible nose weight for your trailer, (the “S“ value on the trailer data plate), and the maximum loading for your vehicle’s tow bar, (usually 80kg to 150kg). This often means that mounting a larger crane at the front of a trailer can easily exceed one or both of these values and result in it being unsafe to use on the road.  Things to consider when choosing a trailer.

  • What is the physical size of the trailer?
  • What is the permissible weight of your trailer when fully laden?
  • Will it be multi-axle? Multi-axles make the trailer more stable but also makes the tow hitch height crucial to keep the trailer horizontal, see below.
  • Will it be braked?
  • What is the maximum nose weight permitted? Is it more or less than the towing vehicle. Which one will be the limiting factor?
  • What is the towing height? Is it compatible with your tow vehicle?

Your Tow Vehicle

Check the data for your proposed towing vehicle. It is all published by the manufacturer and will be on a load plate on the vehicle.

  • Will the total weight of your laden trailer and vehicle be under the maximum allowable mass for the vehicle/trailer combination? Often a fully laden vehicle cannot legally also tow a fully laden trailer due to constraints placed on the vehicle by the manufacturer.
  • What weight can your vehicle pull and is your tow bar capable of handling this?
  • What is the maximum nose weight from the trailer that the vehicle and tow bar can handle? It is usually quite low and often below 100kgs.
  • What is the height of your tow ball? The UK and EU standard is for it to be between 350mm and 420mm when the vehicle is laden. This is particularly important for multi-axle trailers as the trailer needs to ride horizontally with each axle taking equal weight. Also, if you have to lift the nose of the trailer onto the tow ball you will increase the nose weight imposed on both the trailer and vehicle quite dramatically.
Trailer Cranes: A comprehensive guide to cranes on trailers. – Trailer Cranes – Penny Engineering

Factors to be Considered When Mounting the Crane.

Nose Weight.

Trailers are built to have a nose weight when empty to ensure stability. Adding a crane and support frame to the front of a trailer will generally take it above the permitted level for the hitch mechanism and towing vehicle.  One way round this is to add equivalent counterbalance weights to the rear but this is expensive, takes up valuable payload and can make the trailer difficult to tow. Fitting the crane at the rear is more likely to be possible without adding extra weight to the trailer but all trailers are different and need to be assessed. The ideal position for a crane is mounted centrally.


The trailer must not rely on the hitch or jockey wheel for stability when using the crane. Neither is designed for the sort of loads that may be imposed on them. Most crane and trailer combinations have two sliding support legs alongside the crane to go out on either side and also two more support legs that give stability at the opposite end of the trailer.  This second pair of legs often just need to go to ground and may not need to slide out to the side. Some trailers with larger cranes will require ballast in the form of steel plates putting under the floor in the centre of the trailer to add stability. This will affect payload as well as cost.

How is the Crane to be Powered?

Large electric cranes require over 200 amps at peak load. Long cable runs from the front of a tow vehicle to the back of a long trailer will also use up significant energy. This can be offset to some extent by using heavy duty cables, but energy supply needs to be addressed. Are you going to fit a second deep cycle battery and if so, how will it be charged?

A better option for larger cranes is to fit a petrol-powered pump on the trailer although some electrical power will still be needed for safety circuits. This low power circuit is much easier to source from the tow vehicle but does mean that you cannot use the crane without the tow vehicle present. You may need to have a small battery on the trailer to make the whole unit self-sufficient.

Smaller cranes up to 1.0 tonne are more easily powered from the tow vehicle battery due to much lower energy requirements.

Operator Position.

In most cases there will need to be stops to limit the arc of the crane to a specified zone. This is not difficult, but you need to think about where you will be using the crane and where the operator will stand as they need to be in a safe place and not under the crane boom.

What we need to know.

Penny Engineering will help you make sure that you have a successful crane/trailer/tow vehicle combination, but we need accurate data to work from.

The Load.

  1. What are you lifting and how heavy is it? We can weigh items up to 4.0 tonnes for you if necessary.
  2. What are its physical dimensions?
  3. How far from the base of the crane do you need to lift the load?
  4. How often will you need to lift the load? This is the duty cycle.

The Crane.

The data above will help us to specify a suitable crane. We then need to see if it can be safely fitted to the trailer/vehicle combination.

  1. How do you intend to power the crane? Please note that a vehicle battery will never cope with high use.
  2. Where would you like the crane to fit on the trailer? It is likely that a large crane cannot be safely fitted to the front of a trailer.
  3. Where will the operating position be?

The Trailer.

  1. What is the make and model of trailer?
  2. What are the physical dimensions of the trailer and centre of gravity if possible?
  3. How many axles?
  4. What is its empty weight and maximum load capacity?
  5. What is the nose weight empty and maximum permissible nose weight?
  6. What is the hitch height?
  7. Does it have drop down legs to support it front and rear when being loaded?

The Tow Vehicle.

  1. Will the trailer have a regular tow vehicle and if so, what is it?
  2. What is the tow ball height?
  3. What is the maximum load that the vehicle/tow ball can take?
  4. What is the maximum permissible overall combined mass of the vehicle and trailer?
Trailer Cranes – Draft – Trailer Cranes – Penny Engineering

What Information is on a Trailer Data Plate?

Line 5 is extremely important as it gives the maximum weight that the tow hitch can handle. In this case it is 100kgs.  The figure should be preceded by an “0” but often is referred to as the “S” value.  Both have been put on this plate.  How the nose load is measured can give different readings, especially with multi-axle trailers.  The trailer should be horizontal so that all axles share the load, and the tow hitch should be between 350mm and 420mm above the ground to be compliant with UK and EU regulations.

Lines 6 and 7 show that this trailer has two axles each with the same maximum permissible load of 1000 kgs.  In order to reach the maximum all-up weight that this trailer can legally be at 2000kgs you would need to take care not to exceed each axle loading.

Calculating a Vehicle’s Towing Capability

Details of the towing capacity for your vehicle that are found in the owner’s handbook, the manufacturer’s website and on other websites should only be taken as a guide. The actual, exact and only towing capacity figure that should be used for your vehicle is the one that is stamped on the Vehicle Identification Number Plate, VIN Plate.

The Tow Vehicle VIN Plate

Trailer Cranes: A comprehensive guide to cranes on trailers. - LOLER - Penny Engineering

The VIN plate will display either 3 or 4 sets of weights, it is these weights that VOSA or the other vehicle authorities use to determine whether your vehicle is towing or being driven within the law.

  • The top weight ‘A’ is the gross vehicle weight or the Maximum Allowable Mass (MAM) of the vehicle including occupants, fuel and payload.
  • The second figure ‘B’ is the gross train weight, this is the combined maximum allowable mass of the vehicle and trailer.
  • The third and fourth figures ‘C’ and ‘D’ are maximum axle loads front and rear respectively.

The manufacturer’s recommended maximum towing capacity for your vehicle is the gross vehicle weight subtracted from gross train weight. (4200kg – 2505kg = 1695Kg). This calculation is based on a fully laden vehicle. Note that some hybrid and battery vehicles cannot have towbars fitted and so no figure will be entered in position “B”.
We have used information from for this section.

Related Products

Vehicle Mounted Cranes

Our range of cranes that are mounted to vehicles. Typically, these would be 3.5 tonne commercial vehicles such as vans and flatbed trucks.

Vehicle Mounted Cranes - Penny Engineering Ltd

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