Building a Better Boom Truck

Enlarge Image Image 1: Elliott went back to the drawing board for the 32117.

November 16, 2005 • It's easy to think of a boom truck as just a boom truck. This workhorse of cranes is a basic lifting machine without many opportunities for design innovation. But Elliott Equipment Co., Omaha, Neb., is working hard to push the envelope when it comes to boom truck design. As a result, several features introduced this year for its truck-mounted cranes just might make you stop to take a second look. For example, a patented A-Frame outrigger system was shown earlier this year at ConExpo on the newly introduced 32-ton 32105 boom truck. The Super-Link system, which is designed to allow short jacking, is just one of many simple, yet effective, twists on existing technology the company is taking with its crane line.

 

Although not on display at ConExpo with the 32105, Elliott Equipment simultaneously brought the 32117 (Image 1) to market, another 32-ton boom truck available as either a rear- or front-mounted crane. Featuring a 117-foot, five-section boom, the crane offers a tip height of 129 feet. According to Dave Cheleen, factory sales manager • boom truck division, the 32117 is the only 32-ton capacity machine offering a five-section boom. An optional 24-foot lattice jib is mounted on rollers to make it easier to extend. When the jib is swung into place, the maximum tip height is 153 feet.

 

Elliott Equipment's President Jim Glazer said the company interviewed a number of boom truck operators prior to developing the 32105 and 32117. “We listened closely to what they wanted in size, chart, and features, and designed them into this new machine — and our other boom trucks as well,” Glazer said.

 

From the drawing board

Several design decisions on the 32117 have as much to do with the customer as they do the manufacturer. Considering the backlogs on orders that all manufacturers are currently facing, the ability to turn products around faster is a plus for everyone.

 

Featuring a new paint finish, the 32117 boasts an even higher luster than what was previously available from Elliott. Desiring to shorten paint drying time, Elliott Equipment recently turned to Sherwin Williams for its Genesis epoxy enamel product. Certainly the old fire-engine red finish was not substandard, but this new product cures in half the time. A primer coat is still part of the finish process.

 

Elliott Equipment uses a design-build concept for the crane bed, making assembly more turn-key rather than customized. In total, the bed consists of three pieces, which allows for commonality of parts, enabling the bed to be assembled for either a rear- or front-mounted crane. Note that when the crane is rear-mounted, an enclosed cab is available as an option. The center section rides atop the chassis frame rails and acts as a sub-frame, then wings are bolted to either side to complete the bed.

 

Enlarge Image Image 2: Lowering the slewing ring to nearly flush with the sub frame made several other design improvements possible.

A new superstructure, however, is the most significant example of the company's efforts to design outside the box. Conventional designs utilize a shorter slewing ring mounted to a box structure. But Elliott Equipment has engineered a longer, one-piece turret that mounts directly to the sub-frame. By eliminating the mounting box, the slewing ring (Image 2) is installed nearly flush with the sub-frame, allowing room for a standing rotating operator console • for which a patent is pending. Mounting the turret directly to the sub-frame also eliminates a joint in the design, theoretically reducing maintenance over the lifetime of the crane. Note that slewing is non-continuous.

 

Also improving on the geometry of the boom design is Elliott Equipment's decision to pin the boom at the top rather than at the bottom — the purpose of which is to provide more leverage at a low boom angle, subsequently delivering more power out of the hole. In addition, pinning the boom this way provides more clearance for the winch over the truck cab.

  

The operator's stance

A standing operator console that rotates with the boom is a 

Enlarge Image Image 3: The standing backside support was nice but adding a slanted foot prop or seat would be a nice ergonomic improvement.

unique feature for front-mounted cranes. With this design, the operator no longer has to reposition on the other side of the boom as lifting operations dictate, making it easier to keep the boom and load within sight.

 

An adjustable backside support (Image 3) is provided, but we wondered about the lack of a seat, as there seemed to be plenty of room for one. “Although intended to increase comfort and reduce fatigue, I found that leaning back while standing put a lot of stress on my front and back leg muscles,” Guy Ramsey noted.

 

As it is, however, the backside support could be improved with a place to rest your feet. “My natural inclination was to prop my toes up; a slanted foot rest would be a nice addition to take full advantage of the backside support,” Ramsey said.

 

Enlarge Image Image 4: Boom levers offer thumb throttles for the engine and winch.

Meanwhile, keeping the operator's feet on the floor was the impetus behind another patent-pending feature. In lieu of a foot throttle, the 32117 is equipped with a thumb switch (Image 4) located on the top of the control lever to control the engine speed. A two-speed winch is controlled by a similar thumb-operated device. In both cases, Apitech control valves are employed. Backed by a solid reputation, the Apitech valves held true to form in this application. An Eaton/Vickers flow and pressure compensating supply pump complements the valves' smooth operation.

 

In the next issue, we'll discuss how all these features come together to make the 32117 quick to set up and easy to operate.