Visibility and Control

Enlarge Image: Image 1: Pettibone T8044 traversing boom telehandler.

May 4, 2005 • Only a few features clearly set a telehandler apart from its competitors, one of which is a traversing boom assembly that moves forward and backward on the chassis. Just two manufacturers produce models with this unique capability: JLG's Lull and Pettibone's Traverse Lift. The key advantage of a machine with this feature is the operator's ability to move the load horizontally, permitting loads to be landed inside narrow openings, such as windows, or to more readily be able to spot a pallet of material onto
a scaffold.

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Enlarge Image: Image 2: Reach Chart

Pettibone, Baraga, Mich., has been building material handling equipment for more than 120 years and it was the first North American company to produce an extending reach forklift. One of its newer models is the T8044, an 8,000-pound capacity, 44-foot maximum reach machine, which features a boom assembly that traverses 70 inches at any lift height. Introduced in 2000, it was originally sold under the Traverse™ label. The last of the orange Traverse units were built in 2004; today all models carry the Pettibone logo and yellow paint scheme.

I operated a T8044 that was being prepared for the World of Concrete show at the local Pettibone dealer RTS Equipment in Las Vegas, Nev., in January. The T8044 is very much a pick-and-carry machine, but that isn't to say it's not adept with a variety of attachments. A standard quick-attach system features full pressure hydraulic lines running to the boom tip to power an array of tools. It also features a manual quick-release carriage.

Enlarge Image: Image 3: Offset rollers improve right hand line of sight.

The telehandler's transaction boom rides on a massive set of roller bearings. The rollers and the sub-frame that carries the boom are set as low as possible in the main chassis. Look closely in Image 2 to see that the roller opposite the cab is positioned lower than the one closest to the operator. At first, I didn't fully appreciate why Pettibone's engineers had chosen to do this, thinking it was a way to add stability or rigidity to the design.

Enlarge Image: Image 4: For a high-mounted boom design, visibility on the T8044 was impressive, especially with the forks 24 inches above ground level, the most common load carrying position.

In reality, the purpose was to lower the profile thereby maximizing operator visibility to the immediate right of the chassis. It's a difference of only a few inches, but I would later discover how much this design consideration pays off.

  

Enlarge Image: Image 5: Dual lift cylinders reduce boom deflection.

Two main lift cylinders are mounted so that they slightly angle in at the top. This is intended to help keep the boom centered as it is elevated, relieving stress on the entire boom structure. Spherical bearings provide additional stress relief that this mounting angle might produce. According to Pettibone, this dual cylinder design translates into less boom deflection when carrying a load, especially when traveling over rough terrain. One cylinder pulls double duty as a master cylinder, eliminating the need for a dedicated cylinder to keep the forks and carriage balanced.

 

The T8044 boasts a robust construction. The amount of heavy plate steel used is staggering, adding up to a hefty 28,000 pounds of gross vehicle weight. This weight translates into added stability and operator confidence when placing a load with the boom traversed fully forward and 44 feet up. It should also help keep the telehandler's fanny on the ground when exploiting the units 36'1”forward reach.

 

Inside the cab

The operator sits high in the cab, giving a commanding view. But even at 6'5”, I found it a tad higher than I would have ideally liked. Trade-offs! Overall visibility was great, not only to the immediate right, but also to the right rear.

 

Once in the seat, I found myself well-positioned. All key controls were well within reach and dual arm rests allowed for comfortable command. A tilt steering wheel would be a nice addition, though.

 

Most impressive was the performance of the control system. Main boom functions are commanded through a single dual axis joystick with an integral thumb rocker switch for secondary or auxiliary functions. This set-up allows true variable flow for three functions simultaneously. While the pilot-operated main boom functions performed on par with most competitive machines, I was blown away by the performance of the secondary functions. Frame leveling, auxiliary and, in this case, optional frame tilt are metered via a proportional valve commanded by a Hall effect thumb rocker switch located on the joystick.

 

Enlarge Image: Image 6: The view from the operator's seat; analog gauges flip load chart make assessing the situation easy on the operator.

Other operator aids include analog gauges protected by a Plexiglas shield; a parking brake interlock prohibits starting the engine unless the brake is in use; and a low oil pressure alert.

Next issue, get the details on the power and operating systems behind the T8044 and an assessment of its serviceability, along with my overall impressions.