Welcome to our page regarding our 1974 Cheverolet Stepvan Bucket Truck.

We include this page as an interesting reference of our own experiences, in hopes that it might be useful to others in some manner.
 Bucket truck Information
 Bucket truck Drivetrain, chassis and lift specifications
 Bucket truck Pictures
 Bucket truck Resources



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Information


1974 Stepvan bucket truck model fly-around (video may take several minutes to fully load)

The 'stepvan' concept itself is an old one, and comes from the idea that a delivery driver or maintenance person could easily step right from the driver's seat to the curb. More efficient movement at each frequent stop would mean more efficient work. GM built their Stepvan line around this.

Stepvans have been modified into all sorts of things, being a practical, no-nonsense work vehicle. They offer a maximum of cargo room, and a minimum of fuss to access it. It was this idea that created the 'Lamplighter' series of bucket trucks, the concept being that the operator could easily step from the driver's seat right to the bucket to change a lamp, then move to the next one.

These vehicles are fairly rare, although exact production numbers are unknown. In the 70's the GM P30 chassis was used, being a heavy-duty dual rear wheel design. The lift assembly was generally mounted directly centered over the rear axle to provide good balance. The generator to power the lift was mounted to the right of the driver, under the steps to the bucket. Controls are easily accessible within a few steps of the driver's seat, and the driver has only to take a few steps out the door to the right to access the bucket.

We have personally seen both steel and aluminum bodied examples, all supplied with Telsta lifts and rare Onan 3-phase generator sets. Both fiberglass and steel cage buckets were available.

Our specific truck was equipped from the factory with an intercom between the bucket and driver's seat. The vehicle was rated to be driven (albeit carefully) with the bucket in use, so the operator and driver could communicate. It is an aluminum body, with a 2.5kw Onan generator. The drivetrain is a 350 cubic inch engine with a heavy duty TH475 transmission (a factory version of the TH400 with straight cut gears and heavier internals). There are two complete sets of bucket controls, one in the bucket and one in the cab. The generator can be started from the bucket also as long as the key switch in the cab is turned to 'on'.

The lift itself is a turret style, and can spin 360 degrees freely. An indexer on the turret assembly provides warning of too much spinning that would damage the connecting cables, and allows the operator to return the turret to its zero point. The boom is raised and lowered hydraulically, and has a corresponding connection to a cylinder on the bucket that provides automatic leveling. The boom extends with a chain drive electric motor, and spins with another motor. Both are three phase motors. The secondary extension boom is a one-piece fiberglass unit, which nests inside the steel outer boom. Despite the use of fiberglass, this boom is not rated for isolated electrical work.

Our truck was initially ordered by New Jersey Power and Light, as evidenced from paperwork found buried behind cabinets we later removed. It was originally painted yellow. At some point it was later purchased by a fiber optic maintenance company and painted white. The body was made by Union CIty, and the rear axle is an Eaton H110 with 6.17 gearing. This makes for lots of low speed power but abysmal gas mileage.

With the gearing and three-speed automatic transmission, the top speed is about 55 mph without overly stressing the engine. We were informed by a previous owner that although the engine is original, it had been rebuilt many times because of drivers being impatient and unable to maintain restraint with the throttle. This is a heavy (9,000 lbs unladen weight), unwieldy vehicle, and apparently was not being driven as such.

We love the practicality of these trucks. It has a ton of secured and covered cargo space for a bucket truck. It is unique and rare, and beautiful in its ugliness. It's too hot in summer and too cold in winter, being provided with no air conditioning and only a small heater in the front. Hardly any of the windows open, but this is the kind of truck you can open the doors and drive that way. It's horribly uncomfortable and an ergonomic nightmare to drive. In short, it's fun.

1974 Stepvan bucket truck deconstructed and interior model fly-around (video may take several minutes to fully load)

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Drivetrain, chassis and lift specifications


This truck is equipped with a Chevrolet 350 cubic inch engine, with a TH475 transmission (a factory version of the TH400 with straight cut gears and heavier internals). The assessment of the TH475 was later confirmed during a rebuild. The rear axle is an Eaton H110 with 6.17:1 gears.

We have to respect this drivetrain, having survived all these years at the hands of various uncaring drivers. Its purely a work truck, so we assume it was treated as such. The original engine appears to have been rebuilt several times, and we were also passed information of this by a previous owner. This is a truck that should have had a larger engine, but the little 350 served long and with honor.

The engine still has a 4 barrel Quadrajet carburetor, which runs surprisingly well for its age and abuse.

Chassis: tires, 8" x 19.5". Wheels, 19.5" diameter, hub piloted, 10 lugs on 7.25" bolt circle, 5.25" hub bore, Accuride 27775 steel. Brakes, front disc, rear drum, hydroboost power assist.

Lift: Telsta/GCC Model ST36, Serial 4368, 300 lb. capacity, 31' platform height, 1500 PSI max. hydraulic pressure, non-insulated

Generator: Onan 2.5kw 3-phase, model 2.5LK-8R 1O433E. The generator set is push-button start, using 12v DC to energize the field coil and turn the engine over. This generator is not equipped with a 12v generator, so it relies soley on the truck engine generator to recharge the batteries used to start and run the engine. This truck has a dual deep-cycle battery setup with an isolator switch in the cab, so that the generator can be isolated to one battery leaving the other to start the truck if it runs dry. There is a 120v single phase take-off outlet in the cab on the generator control panel. These little 3-phase generator sets are rare, and most appear to have been manufactured by Onan specifically for Telsta lifts.

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Pictures


1974 Chevrolet Stepvan Bucket Truck

1974 Chevrolet Stepvan Bucket Truck

1974 Chevrolet Stepvan Bucket Truck

1974 Chevrolet Stepvan Bucket Truck

1974 Chevrolet Stepvan Bucket Truck

1974 Chevrolet Stepvan Bucket Truck

1974 Chevrolet Stepvan Bucket Truck

1974 Chevrolet Stepvan Bucket Truck

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Resources


We found these resources valuable for maintenance, or interesting:

     Onan generator LK operator's manual 1
     Onan generator LK operator's manual 2
     Onan generator LK parts manual 1
     Onan generator LK parts manual 2
     Onan generator LK service manual

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