Engineering Design Consultants

Sandsend Mule

Eadon Consulting were approached by Balfour Beatty in the autumn of 2014 to design a MULE (Mobile Unit Lifting Equipment) which would be used to transport and lay revetment units used as part of a 900m coastal defence project in Sandsend, North Yorkshire. Balfour Beatty had realised during the tender period that to install the revetments would require closure of the A174, a key road linking Sandsend to nearby Whitby. This closure would mean significant disruption for the local community. They consulted with their engineering team who had experience of installing the revetments and they came up with the outline initial concept. It was this outline concept that was brought to Eadon Consulting for further development into the detailed design used on site.

The MULE carries revetment units along a pre-built track at around 2km/h and then lays them into the correct position using the machines 3 adjustable legs to ensure accuracy. Each of the legs is able to vary its height and angle with the aid of hydraulic cylinders. The machine, which consists of a main frame on which the revetment is loaded, has a counterweight section at the back on which the hydraulic power pack and diesel generator are located. The machine is moved by a separate unit attached to the frame via a specially designed coupling.  The drive unit uses two hydraulic motors to drive the drive wheels sitting in the same guide channels and also has additional ballast which is provided to ensure the drive achieves the required traction.

Eadon, who were the mechanical and structural designers on the project, carried out all of the calculations and the development of the concept. The project also saw engineers continue through to the detailed design and 3D model and manufacturing drawings. The team found that the project presented several challenges during the process and were required to make significant changes to the mechanism and strengthening concepts to ensure the MULE functioned correctly. Environmental factors also had to be taken into account as the machine is required to work in a hostile, coastal environment. The design team also had to bear in mind that the client ultimately wanted a cost effective solution.

Work on the beach, which lies just north of Whitby, has been complete and all 360 revetments were successfully laid into place by the 5200kg mule. The completed project will protect the area from further erosion.

The project was awarded a Yorkshire Region Institute of Structural Engineers Award for Best Medium Sized project by a Small Company, recognising the innovation that the machine brought to the project and the direct benefits for the contractor and local community.

The MULE is demonstration of the power of collaboration between contractor and designer. Balfour Beatty had identified a problem with the usual method of installing coastal defences in this location. They realised that an innovative solution could be applied. Through creative thinking, Eadon Consulting delivered the design of a moving structure which bought safety, economic and efficiency benefits to project and also the local community in the form of reduced local disruption.

For more information regarding our bespoke machinery design services or to discuss your bespoke machinery requirements, please telephone 0114 399 0400 or email us.

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