A Harsh Reality
The Idaho Transportation Department has many trucks on the road every day to perform construction and maintenance across the state highway system. One of those trucks – an 2006 Mack® Granite™ – had been outfitted with an Altec® digger/derrick body so that it could be used to install and service traffic signs. A boom mounted behind the cab had an auger for drilling holes as well as a bucket for reaching signs.
The chassis for this truck included an 18k front suspension and a 40k rubber block rear suspension. By late 2013, the truck had approximately 70,000 miles on it – and had been racking up countless complaints for over 18 months.
The ride of the truck was harsh; so harsh, that the State of Idaho had concerns about driver wellbeing. Because the rubber block suspension continued to collapse after being repaired, there was virtually nothing to absorb the vertical accelerations seen in normal day to day driving, much less off road conditions – resulting in reduced in-service time for the truck.
A Series of Setbacks
The chassis had to be fixed. Since there were a limited number of these trucks available, having a truck out of circulation or having drivers restricted from using it created serious complications in keeping up with necessary sign installation and maintenance.
The Idaho Transportation Department contacted their regional Mack® truck dealer, Northwest Equipment Sales, for help. Northwest Equipment made several attempts at resolving the ride issue. Rubber blocks in the suspension were replaced, leaf springs were removed, tire pressure was changed, a progressive-rate overload bumper was installed and even heavy-duty air ride seats were finally put in. But despite the fact that repair costs kept mounting, any relief the repairs provided would only last about two weeks. Then, the ride would again become severe and painful for the drivers.
Northwest Equipment made inquiries with the manufacturer of the existing rear suspension, asking if anything could be done. They were told that the problem was not with the suspension, and that a new chassis – valued at approximately $175,000 – would be required.
The Solution: A New Perspective
In search of alternative options, Northwest asked Link Manufacturing to come out in August 2013. Link had provided other products to the Idaho Transportation Department, but this would be the first Air Link suspension.
Joe Chadwell, Western Regional Sales Manager for Link, and Benjamin Langton, OEM Sales Engineer, examined the truck. “We knew that the chassis dynamics played a huge role in this,” stated Langton. “There was a very stiff chassis with a quivering boom on top of it. The vibration of the boom was being transferred from the rigid suspension and frame into the driver’s cab itself. That was the cause of the harsh ride and the resulting injuries.”
Link had a solution: the Air Link® Tandem Drive Suspension. Chadwell explained, “Air Link is unique because it combines two proven suspension technologies. First, we use a walking beam that links the front and rear axles together, providing load equalization. We then incorporate an air suspension that delivers a softer ride than a mechanical suspension.”
The solution was viable because it could be retrofitted into the existing chassis suspension. Northwest was in favor of the recommendation and secured approval of the retrofit, which took place in October 2013.
“Link’s greatest value was that they determined the root cause of the problem, and developed and supported the installation of the solution,” said Jerry Schafer, General Manager of Northwest Equipment. “Other suspension providers offered air suspensions or walking beam suspensions: only Air Link combines the two.”
An Expert Installation
Installation of the Air Link suspension took place with a minimum amount of downtime for the truck. Present and overseeing the installation was Dan English, a member of the original Air Link suspension development team. “We wanted to ensure that we were prepared for any and all variables, and Dan was clearly the best man to supervise the process,” said Langton.
An Enthusiastic Response
Following the installation, the truck was test driven by the service manager and the crew boss from the Idaho Transportation Department. They were astonished at the quality of the ride, and affirmed that the result exceeded their expectations.
The real test, however, was what the drivers would say after using the truck for a normal workload. Steve Spoor, Maintenance Service Manager at the Idaho Transportation Department stated, “Our drivers literally gushed over the drastically improved ride. Gone was the constant slap-in-the-back that had existed with the previous suspension.”
But driver health and attitude were not the only benefits. The Air Link suspension improved uptime for the truck since additional repair attempts would no longer be necessary, and it eliminated the need to replace the entire truck chassis.
Both Northwest and the Idaho Transportation Department were impressed with Link’s support and with their sense of urgency in solving this problem. “Link is about providing solutions,” said Chadwell. “Our opportunity in the market lies in our willingness to go above and beyond to ensure customer satisfaction.”