Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/578350
October 2015 | EquipmentWorld.com 28 The goal: Productively move a full payload in sometimes extreme underfoot conditions by keeping all wheels engaged with the ground at all times. Here's how today's articulated dump trucks do it. INTELLIGENT TRACTION MACHINE MATTERS: How automatic traction control works S tandard on articulated dump trucks, auto- matic traction control (ATC) monitors wheel- spin and axle speeds several times per sec- ond and responds quickly if slip is detected. With ATC the truck is always in the correct drive combination for condi- tions. And ATC is flexible; it can be applied to a single wheel, one or more axles, all wheels on one side, etc. Traction control saves money. Volvo, for example, says ATC improves produc- tivity and fuel consumption is reduced up to 6 percent. Because ATC-equipped trucks are easier to operate, op- erator training times are shorter. And since these trucks can take on rough conditions, including steep hills, you don't have to spend as much to maintain haul roads. To take a deeper dive into how an ATC works, let's look at the Komatsu Traction Control System. Monitoring the relative speeds of the front and center axles, when slip is detected, the system automatically engages an inter-axle lock. If a wheel is still slipping, the system applies the service brake to that wheel and continues to monitor wheel speed and modulate braking. In the cab, the operator uses a rocker switch to choose between automatic and manual opera- tion of the inter-axle lockup clutch. Doosan ADTs use one turn- ing ring on each rear tandem housing and one at the ar- ticulation joint. The rings on the tandem housings allow extreme positional differences between the front and rear wheels of each tandem. The front turn ring allows the cab to rotate independently of the rear frame. In addition to applying braking to a wheel that's slip- ping, Doosan ADTs use longitudinal differential locks that, when engaged, provide a 50/50 power split be- tween the front and rear axles. The front and rear axles have limited-slip differentials. Sources Neville Paynter, president, Bell Equipment North America Anthony Pollock, AT Marketing, Caterpillar Brian Bereika, ADT specialist, Doosan Mark Shea, ADT product consultant, John Deere Joe Sollitt, product marketing manager, Komatsu America Henrik Larsson, product manager, Volvo Construction Equipment