Design Challenge - November 2013

Lance Procter - Strong-Arm Tactics

lanceCommercial aviation is a difficult business, and as it becomes increasingly competitive, aviation companies will begin to take more notice of their ground support equipment.

Aircraft towing tractors have traditionally been over-specified because of management fears they will pick too small a unit. Alongside this, many of them have been fitted with lots of accessories, most of which do not improve performance.

To provide more cost-effective tractors, operators will be forced to move towards simpler vehicle designs based on construction and agricultural vehicle components, and deleting much of the traditional bodywork and accessories*. To improve productivity, they will move away from the use of separate towbars, towards an integral robotic arm capable of attaching to a range of aircraft.

Separate towbars can often be a real problem operationally, particularly when handling different models of aircraft, because the right towbar needs to be found and connected before the tractor arrives at the aircraft. This involves additional personnel, and often another vehicle just to handle the towbars. Towbarless tractors have certainly solved this problem, but at a high cost of purchase and complexity.

Tractors not only tow aircraft, they also handle the steering too, and conventional towbars incorporate sacrificial shear pins that are designed to fail if the steering torque or drawbar pull exceeds a specified limit. Our StrongArm design therefore incorporates sensors to advise the driver when these limits are approached, enabling it to detach from the aircraft if a jackknife is imminent. Jackknifing is often a result of wet conditions and tail-heavy aircraft loading,  and presents a real danger in conventional aircraft haulage.
The StrongArm would extend from the tractor and attach to the aircraft tow points without the need for any outside assistance. In operation, it will guide the driver to impose minimum loads on the nose gear and help prevent dangerous conditions from arising.

The off-centre cabin is configured to hydraulically lower for under-fuselage towing, and to assist vision when connecting. During most towing or push-back operations it can be raised to provide an improved view of the work environment. Crab steering is already common on tow tractors as it is purported to move the vehicle sideways more quickly than normal steering, and in turn steer the aircraft more quickly. However, most operators don’t really understand it, so it is rarely used – except perhaps at particularly cramped airport gates.

Together, simpler tractors and better towing connections will permit more efficient and cost-effective aircraft handling.

* Lance talked about some of these issues in a blog for iVT in 2011. Read more at IVT Industry Blogs

More images from Motive Power

* Click on a thumbnail below to view a larger image.


HI-VIZ, LOW DATA / Jouko Polojärvi HI-VIZ, LOW DATA / Jouko Polojärvi HI-VIZ, LOW DATA / Jouko Polojärvi



Motive Power

As a director of Motive Power in Sydney, Lance Procter specialises in designing complex vehicles. Many have related to mining equipment, and he’s designed towing tractors for heavy aircraft up to A380 size





>>Back to Design Challenge November 2013