Tiffin Motorhomes Tours

Powerglide Chassis Plant Tour

In recent years Tiffin Motorhomes decided to build their own chassis in addition to offering chassis built by Freightliner and Spartan. This gave Tiffin the ability to design the chassis the way it best fit their needs rather than adapting their coach to fit any available chassis. It also gave them the ability to administer strict quality control and make quick response changes as desired when compared to chassis supplied by others. The chassis was designed by Gary Jones, who penned the Peak chassis used in the Alpine Coach motorhomes. This chassis was enthusiastically endorsed by it's owners as the best handling chassis of any class A motorhome. After taking a number of years to properly design and engineer this new design for Tiffin Motorhomes, the Powerglide was eventually launched to rave reviews. I previously tested and reviewed a Powerglide chassis on this website at This Link, so I won't go into detail as far as repeating it's benefits. The Powerglide chassis is built in a dedicated plant on the Tiffin Motorhomes complex. While it's not part of the public tour, I was given a tour by Brad Warner, the product engineer and also met with Gary Hart, the plant manager. In the following photos I'll take you through the Powerglide plant.

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Powerglide Assembly Line

The Powerglide chassis plant is divided into three assembly lines. One line is dedicated to the Allegro Bus chassis assembly, while a second line is dedicated to the Phaeton chassis. A third line is now being laid out to handle production of Tiffin's new Breeze motorhome, which will also have a Powerglide chassis especially designed for the Breeze.

Powder Coated Frame Rails

Most chassis are assembled with riveted crossmembers. The Powerglide uses huckbolts therefore all of the frame members can be powder coated prior to assembly. These frame rails lie on a side table and are ready to move to the assembly table as the first step in the construction of the chassis.

Frame Assembly Table

The frame rails are carried by overhead crane to the assembly table. On this perfectly level surface the various components are aligned and huckbolted together when held in assembly jigs.

Fitting the Axles

Once the basic frame rail structure has been assembled axles are fitted beneath the chassis. This particular chassis is a 43' Allegro Bus so the tag axle is fitted first, then the rear axle will be placed alongside it. The Breeze prototype can be seen in the background.

Front Axle Assembly

In like manner the front axle is fitted beneath the frame rails. Tires will next be mounted to allow easy movement of the chassis during the assembly process.

Huckbolted Chassis

This image gives a good view of the many huckbolts that are used to hold the chassis together. Huckbolts are a superior fastener when compared to the rivets used in most chassis construction. This particular chassis is a 40' Allegro Bus so it has no tag axle. At this point the basement cargo sub-frame structure has begun to be added to the chassis frame rails.

Engine Installation

The engine and transmission assembly is now added to the chassis and mated with the rear axle. At this time additional components are installed.

Allegro Bus Fan Drive

The Allegro Bus uses a side radiator. Rather than use a hydraulically driven fan mechanism, the Powerglide uses a mechanical drive system. This system uses a belt driven fan clutch, visible in the foreground, that turns a driveshaft that connects to a right angle gearbox that drives the radiator fan. The fan will engage as needed in response to the engine's ECM.

Air Tanks

The air tanks and air lines are installed after the engine has been mounted. The Powerglide chassis utilizes three air tanks near the rear axle.

Powerglide Phaeton Chassis

Recently introduced is a Powerglide chassis designed for the Phaeton. This is a rear radiator chassis with a solid front axle. The Phaeton version of the Powerglide chassis utilizes a new method for attaching the sub-frame structure whereby the sub-frame is attached to the sides of the frame rails rather than suspended from tubing welded above the main frame rails. This allows for an extra 2" of basement storage height beneath the frame rails.

Batteries and Electronics

This image of a Phaeton chassis shows the battery location as well as some of the relays, solenoids, and multiplex breakouts.

Vansco Multiplex Wiring

The Powerglide chassis incorporates a Vansco multiplexed wiring system. This system eliminates the many fused circuits and minimizes potential electrical issues during the service life of the chassis. The front most compartment, beneath the driver's seat, contains the Vansco controller module as well as the diagnostic LEDs and data buss connection.

Generator Installation

Powerglide chassis receive their Onan Quiet Power Diesel generator at this station. the generator set is mounted on slide-out rails for ease in service access.

EPA 2010 Engine

The 2010 EPA emissions specs require some sophisticated emissions gear on the new engines. Cummins uses SCR injection to meet these requirements. This shot of the prototype Powerglide chassis with the EPA-2010 emissions gear in place shows the complexity of this system. In addition to the EPA-2007 spec Diesel Particulate Filter (DPF) this system also has an SCR for urea injection. These units are now stacked vertically. Extensive electronics manages the urea injection.

Urea Tank

The EPA-2010 specs require a reservoir tank to hold the DEF (Diesel Emissions Fluid), also known as urea. This poly tank is located in a dedicated curbside compartment.

Mark Quasius - "Cruzer"

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