Recycling Powertrains With Glider Kits
Builders of front-discharge concrete trucks still employ a once-common method of stretching component life while preparing for '07 diesels.
By Tom Berg, Senior Equipment Editor
Glider kits – the installation of existing powertrain components into a new chassis – is all but gone from most of the truck-building scene, but it's alive in the unique world of front-discharge mixers. Two manufacturers in the Midwest produce glider-kitted mixer trucks even as they prepare to integrate '07-model engines into their lines of new vehicles.
Indiana Phoenix and Terex Advance, whose plants are in the northeastern part of the Hoosier state, receive tired "donor" trucks from customers and transform them into rigs that look new and perform almost like new.
On average, glider kits make up about half the business at Phoenix. The company actively promotes the concept, says its sales manager, Dave Byerly. They're a much smaller part of Terex's output, but they are expected to become more important early next year when more costly diesels must be installed in new trucks, says Ted Decker, director of operations.
Engineers at the rival companies are investigating what changes must be made to their rear-engine vehicles to accommodate the new, hotter-running diesels and their emissions-reduction equipment. As with conventional front-engine trucks, Phoenix and Terex mixer chassis will need larger radiators and better air flow to cool the 11-liter Cummins and 13-liter Caterpillar diesels that will go in their new vehicles.
They anticipate using the aftertreatment devices selected by the engine makers.
Ready-mix trucks are good candidates for glider kitting because they usually see low annual mileage. Operators run them locally, and those in northern states are parked in winter months and other times when inclement weather shuts down outdoor construction activity. So although the trucks stay in fleets a long time, their powertrains still have considerable life by the time corrosion and rigorous use have worn out other parts.
The front-discharge configuration – the only type that Phoenix makes and a major part of Terex production – costs considerably more than a rear-discharge truck, which is another incentive for operators to get more use from an existing powertrain.
A glider kit (so-called because it's engineless and could only glide if given a hypothetical push) consists of a new main frame, trimmed cab, wiring and lights, fenders, front bumper, fuel and water tanks, and sometimes suspensions. Usually most of the mixer body is also new.
Into the new chassis go the customer's used engine, transmission and axles. That's the minimum list of used parts installed in a glider for it to avoid classification as a new truck, explains Phoenix President Dan Biberstine, who has worked in this niche business since 1968.
Gliders are registered in the model year they are produced, but if they include those components, they are exempt from the 12 percent federal excise tax applied to new Class 8 trucks. This adds to the savings, though most of the saved money accrues from re-using the otherwise expensive engine and axles.
The price of an assembled front-discharge glider now is about half that of a new mixer truck, Byerly says. A glider's price might become an even smaller fraction in January, when more costly 2007-model diesels, along with particulate filters and larger cooling packages, must be used in new trucks.
Workers at the Phoenix plant in Avilla, Ind., west of Auburn, have kitted old Advance and Oshkosh front-discharge mixers, as well as some rear-discharge mixer chassis from various manufacturers. The make and type of chassis are almost irrelevant, because only powertrain parts are re-used, and all become front-discharge mixers. Condition of the powertrain parts is the customer's concern because he knows them best, Biberstine says. Workers clean and visually inspect the components and can arrange repairs and overhauls, but usually they are installed as received.
Most front-discharge chassis have front-driving axles to enable them to wallow through mud and sand to get to work sites. Most front and rear axles are Meritors – "Rockwells" to many old-timers – because over the years they have proven to be rugged and are supported well by factory reps, says Terex's Deckard. All of these heavy trucks of course have tandem rears and, depending on the desired payload and weight laws in states where they'll run, often have various types of lift axles and axle spreads.
Many engines that go into gliders are clean-burning electronically controlled models because they were mandated in vocational trucks in the mid '90s, and are showing up in the donors that customers send. Biberstine and Byerly let me drive a kitted Phoenix – an industrial equivalent of the mythical bird that arose from ashes to fly again. The truck had a 350-horsepower Cummins M11E with an exhaust that was smoke-free upon startup and remained clean as I scooted up and down the street in front of the plant.
The five-axle truck was owned by a customer in Michigan, so for liability reasons I didn't take it onto busier public roads. Its 4000-series Allison HD automatic transmission made the truck easy to drive and maneuver, and it rode rather smoothly. The truck's low-slung, one-man cab sits in the center of the chassis under the body's loading funnel and discharge chute. Visibility was excellent in all directions except to the very rear, but the mirrors were large and well placed, and a backup camera with in-cab screen is an option. The cab is made of stout stainless steel to withstand cleaning chemicals commonly used in the ready-mix business.
The Allison is a key component in a front-discharge mixer because the driver operates the chute at the job site. The chute is right in front of him because he drives right up to where the concrete must be poured. He uses a control stick in the cab to raise and lower the chute and swing it left or right, and moves the truck up or back and repositions it as needed. While doing this he controls drum output by speeding or slowing its rotation with a foot pedal. A manual transmission and clutch would add work and slow the pour.
Phoenix also uses its rear-engine chassis to mount water-spraying and dirt-slinger bodies. Experience with a square-bodied slinger – whose belt-equipped chute throws top soil and aggregates where customers want the materials – taught Phoenix that just moving the muffler away from the path air takes on its way to the radiator can improve cooling, explains Byerly, the sales manager. This is one of the changes it expects to make for '07 diesels.
Engineers at Terex Advance in Fort Wayne are investigating air flow past the mixer drum with an eye to keeping it moving toward the rear-mounted radiator, says Jim Yakel, vice president of engineering.
Drums on front-discharge mixers are comparatively narrow for reasons of weight distribution and the need to position the chute above the cab, where it can reach forward to pour concrete. This already slender profile will help in cooling the '07 diesels.
Gliders were somewhat popular among owners of highway trucks in the days when overhauling and rebuilding were more common. They were also a way to re-use a still-good powertrain from a truck or tractor that had been badly wrecked. But kitting has all but disappeared as component and chassis life have increased. Also, chassis have become so electronically complex that it's more difficult for fleet and dealer mechanics to assemble a glider.
Truck builders say freight haulers almost never ask about gliders as a way to sidestep upcoming price premiums on '07 trucks. Builders say that's not likely to change, even if the practice is alive and active among some mixer operators.
