Coming to a road near you!

[snowsub]

well not in the immediate short term....
(it's being trialled in Queensland & Victoria at the moment)

Trackaxle
(Self-steering axle technology for track trailers)



The Trackaxle is an active self-steering system fitted to trailers, which improves the truck's low speed steering capability. A Locking mechanism engages for operating at highway speeds.

the technology reduces road damage caused by tyre scrubbing around corners. It is also safer and less disruptive in traffic. Heavy vehicles aften need to pull-out to the right to make a left turn. Because the Trackaxle needs less space to turn, the disruption to traffic and risk of cars attempting to overtake on the inside is reduced

Many long load systems use a ride on steersman to negotiate tight corners. Some devices employing a pivotal rear bogie have been successful initially, but have developed poor tracking behavior as parts began to wear, a risk associated with having too many moving parts. Trackaxle was different in that it had very few moving parts and was self steering, yet it took an aspect of the command steer system and used it to modify the self steer.

Details:
On a semi trailer, the trailer is directly coupled to the prime mover, meaning directly linked or connected to the prime mover through a turntable on it’s front end which mates with a vertical axis pin that allows prime mover movement for turning. The freight trailer is independent of the prime mover as the front turntable and the back wheels support it.

In United States and Australia, semi trailers usually have 3 axles, the front, or steer axle having two wheels, and each of the two rear drive axles having a pair of dual (double) wheels on each side. Therefore, the most common configuration of a semi-trailer is a vehicle with 10 wheels. The three axles on a standard trailer are mounted in straight alignment on the frame of the trailer.

Trackaxle is an improved trailer axle set that is a self-steering system designed to closely follow the path of a prime mover.

The trackaxle system comprises of:
§ A subframe which supports the axle group (three axles)
§ Control rods that steer the subframe
§ Hydraulic steer links that steer the control rods and front and rear axles
§ The steer control and steer limiter mechanism
§ Remote control in driver’s cabin for wireless reversing

A Trackaxle trailer has three axles mounted on a sub-frame, which attaches at its mid point to the frame of the trailer by a ballrace turntable. A ballrace is two circular plates with ball bearings between them, the ball bearings allow the turntable to roll smoothly around.

The middle axle is mounted to the sub-frame directly under this turntable, but the front and rear axles are mounted to the sub-frame by low profile turntables so they can rotate under the sub-frame. Two steer links connect these axles to the body of the trailer near the centre of the ballrace so that when the prime mover pulls the front of the trailer round a corner and the sub-frame wants to go straight on, axle 1 and axle 3 rotate in opposite directions to form a concertina which steers the sub-frame round the corner.

There is a hydraulic linkage, the limiter, between the front of the trailer and the sub-frame at the rear. This puts pressure on the sub-frame to keep it in a straight line. When the prime mover turns sharply, it removes this pressure, allowing the sub-frame to rotate freely. When the prime mover comes back to a straight line the limiter puts pressure back on the sub-frame to straighten up after turning. This makes for more predictable turning regardless of road conditions.

In straight highway travel, a highway lock holds the sub-frame straight. The prime mover needs to veer off line by more than two degrees for the lock to disengage. This makes Trackaxle very stable on the highway.

The sub-frame will also lock under heavy braking before there is any risk of brake lock up. This prevents any directional instability in a skid.

The Command steer reversing remote control allows drivers to use a wireless remote similar to a garage door remote to steer the rear sub frame of the trailer while reversing, either left or right. In reverse, the two steer links are unlocked from the trailer body and locked to a motor driven steer plate, which the driver controls with his cabin switch. Command steer removes stresses on the trailer and lets a driver put his trailer into tight locations, reducing time taken for deliveries and increasing volumes delivered.




Summary of benefits of the Trackaxle
1. Productivity
§ Improves access to more of the road network
§ Major benefits for manoeuvring semi-trailers in urban traffic
§ Improved efficiency of traffic flow.
§ Allows the trailer to follow the path of the prime mover.
§ Demonstrated 30% productivity boost (that is amount of goods delivered per journey) over conventional heavy vehicles due to access to greater number of roads, causes less disruption in traffic because it does not have to swing wide at intersections and roundabouts (time efficient).

2. Safety and Infrastructure
§ The three-axle system takes up less road when turning and causes less disruption in traffic because it does not have to swing wide at intersections and roundabouts.
§ Reduced tyre wear due to less scrubbing on the road
§ Reduced impact on road wear and tear
§ Less damage to road furniture (roundabouts and signage)
§ Reduction in cost to local authorities

3. Less Pollution
§ In urban operation, it uses 40% less engine power when turning left or right than conventional semi-trailers. It doesn’t have to overcome the resistance of dragging tyres, therefore the vehicle exerts less energy whilst moving and it travels faster.

http://www.trackaxle.com.au/home.htm

Road Transport Dynamics Report
http://www.trackaxle.com.au/docs/rtdynamics.pdf

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This'll be interesting to see out on the road, also safer when negotiating a 2-lane round-about with a truck in the left lane (both going straight through).

Just thought I'd throw this out there as something different and interesting