T he versatility of demountable bodies is underlined nearly every day
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of the week by Parkfield Southwest, the Devon-based transporter of PVC-framed patio doors and window units. Twoand-a-half years ago the Torquay company added an Isuzu NPR 6.2-tonner with a demountable body to its fleet, and it has been more than pleased with its performance, says managing director lan Smythe.
A typical journey will take the Isuzu from Torquay to the Midlands, taking in several deliveries on the way. The driver will arrive at the Birmingham factory of one of Parkfield's key suppliers, demount the body and pick up a loaded one.
He will take it back to Torquay while the empty body he left behind is replenished, returning to collect it three or four days later.
Empty body
This means that the driver does not have to waste time hanging around while his vehicle is loaded, and gives the factory the chance to refill the empty body at its convenience.
One of the swap bodies is fitted with a curtain on the nearside but is solid on the offside. Built by Bovey Commercial Bodies, of Bovey Tracey, Devon, it is 5.2m long, alloyframed and uses a Ray Smith Group (RSG) underframe and demount gear. It also has a Luton head which doubles as a sleeper compartment for the driver.
The Isuzu usually carries a load of 2.5-3.0 tonnes. But because glass is a heavy product to transport, Stnythe is looking at acquiring a 13-tonner. RSG, like its rivals Abel Demountable Systems and Cartwright Group, is a leading supplier of demount systems. Over the years RSG equipment has appeared on trucks sporting the colours of Argos, Bosal, Domino's Pizza, Londis and Pirelli, among others.
There are two basic demount systems: the contact type and the straight lift. The former relies on the chassis being equipped with either rear air suspension, or one or perhaps a pair of hydraulic cylinders if the vehicle is on steel suspension. The body is held in place by two twist locks at the rear and a speciallydesigned bolster at the front to which prongs in the front of the body locate.
When the driver arrives at his destination, he releases the twist locks, raises the air suspension or hydraulics and lowers the rear legs. He then lowers the air suspension/ hydraulics, drives forward until a safety stop engages, lowers the front legs and pulls clear.
When he goes to pick up a body, he reverses underneath it. Rollers beneath the body will ride up a ramped track on the chassis, which lifts the body clear of the ground.
The front legs are folded away and the driver continues to back up until the body locks into place. The rear of the vehicle, or body, is raised to allow the rear legs to be stowed.
With the straight lift approach, the chassis either has to be equipped with front and rear air suspension or rear air suspension plus a pneumatic lift pack, or two pneumatic lift packs. To drop the body the driver releases the twist locks, raises the body to allow the legs to be folded down, then lowers the lifting devices and pulls away.
When he collects it, he reverses under
neath, raises the body so that the legs are off the ground and can be stowed, and then locks it into place.
Abel sales director Malcolm Brown says: "Companies can use demountable bodies as cost-effective warehousing, loading them with goods as soon as they come off the production line, then storing them ready for delivery to customers. Because goods go straight into a body there's less handling, and less damage."
But the weight of the baseframe, twist locks and legs brings a typical weight penalty of 300kg, Brown points out—more if a pneumatic pack has to be fitted. 'However, payload only becomes an issue at 7.5 tonnes and below," he says.
It costs £6,500-7,000 to prepare a chassis to take a swap body, and a 25ft curtainsider swap body can cost L7,000-8,000, he adds. Careless drivers can easily harm demount equipment. Bump a leg at low speed and it will probably survive. But bash it hard and it could cost izoo to replace.
Brown warns that if the driver is inexperienced or sloppy, damage can also be done to the chassis guide rail on a contact system. "Because of this we offer driver training to our customers," he adds. The first session is free, with a charge for subsequent sessions.
"We've got customers using demounts to transport everything from fridges to packaged oil," says Brown. "However, there's been no big increase in interest in swap bodies for intermodal work."
Demount bodies tend to
last if they are looked after. Brown knows of one customer running bodies that are 20 years old, and ro to r5-year-old bodies are relatively common.
Theft may be a worry if a swap body has to be left unattended, Brown agrees, but the thief would have to turn up with a suitably equipped chassis. "And the bodies that operators specify vary so much that the odds are that he wouldn't be able to pick it up," he says.
Demounts remain a popular choice among many operators, says Cartwright Group director Steven Cartwright. His company has just supplied 34 swap bodies to bed manufacturer SilentNight, taking the total it has in service to zoo. They are used on a fleet of drawbars and allow drivers to take two laden bodies for delivery, while two others are being loaded back at the warehouse.
Drop area
"A drawbar demount operation enables drivers to trunk to the drop area, and leave the rear box and trailer at a secure location while the vehicle proceeds with the front box to deliver its load," says SilentNight fleet engineer Dave Livesey. "The unit and empty box then return to pick up the remaining full box so that the driver can make a second delivery run. Delivering to mail-order addresses, often on housing estates, is much easier with a single vehicle and body than using an entire drawbar combination. When both containers have been emptied the driver returns to base with the trailer."
Demounts require little maintenance other than periodic greasing of the legs, says Cartwright. If hydraulic rams are fitted, oil levels and the integrity of the seals should be checked regularly.
• For more details of the individual demount systems provided by the various manufacturers, refer to Product Roundup in last week's issue (CM i3-i 9 April).