Easy to Spot in a Crowd

Editor's Note: In anticipation of the upcoming 2007 Telehandler Showcase, Lift and Access 360 will be recapping articles on machines that were featured in the 2006 Telehandler Showcase. These articles were originally published in the February 2007 edition of Lift and Access.

Enlarge Image The Gradall 544D10-55 was one of two Showcase machines with a truly unique design.

September 12, 2007 • The Gradall 544D10-55 was one of two machines • the other being Lull 1044C-54 • at the 2006 Telehandler Showcase with a truly unique design. Its blue exterior makes it easy to pick out of a crowd, but that is not the only thing that makes the Gradall telehandler, built by JLG Industries, McConnellsburg, Pa., distinctive. Its axle configuration features 90° pivot-steering.

The rear-pivot design keeps the outside turning radius at only 178 inches, which is less than the overall length of the machine • a major selling point. Only the recent advent of tighter 55° turning axles on competitive machines has allowed larger, longer wheel-based, four-wheel steer machines to compete with this capability. However, a more complex design, more service points, and possibly more wear-point potential are the trade-off that comes with the ability to pivot 90°.

Enlarge Image The rear-pivot design keeps the outside turning radius at only 178 inches.

 

Independent hydraulic drive motors coupled with Fairfield torque hubs power each rear wheel. The front axle is a rigid, limited slip design supplied by Carraro. On the floorboard of the cab, a separate pedal is used for differential axle lock. When depressed, in conjunction with the accelerator, this traction lock splits the oil flow between the front and rear axles. A separate set of relief valves protects the rear-drive motors from any pressure spikes.

 

The Rexroth-supplied hydrostatic transmission is sensitive to engine rpm. Maximum operating pressure is 6,300 psi, and the transmission comes online when the 125-hp John Deere 4045HF275 Turbo engine is turning at about 1,100 rpm. Another feature of the hydrostatic drive is the ability to de-stroke the pump, which is accomplished by depressing the brake pedal halfway. De-stroking the pump allows the operator to inch, or feather, the drive and/or brake with the use of one pedal. It also allows the drive speed to be regulated independently from the engine speed.

 

Because all controls are pilot-operated, there are no electronics involved in the direct operation of the machine. On a standard unit, controls are grouped on the right side of the steering column. An optional left-hand fork tilt, frame-leveling control is a very popular option on the west coast.

 

The 544D10-55 has a fairly long wheelbase and a very low center of gravity, which translates into greater lifting capabilities and added stability when carrying a load over rough terrain. The machine lifts 4,000 pounds to the maximum 55-foot lift height without the use of outriggers; however, outriggers are required to take 3,000 pounds to full horizontal reach of 42 feet. Primarily a pick-and-carry machine,

Enlarge Image The hydraulic oil filler is located right next to the fuel filler, so keep a lock on the cap.

the unit offers great visibility to the side and rear when a load is in the carry position. Good visibility is due in part to the low engine mount and boom support structure design. While this particular mid-mount engine is not the easiest of the group to service, most critical service points area accessible.

 

Other points: Tires have Hydro-fill for stability. The hydraulic oil filler is located right next to the fuel filler, so keep a lock on the cap. JLG has gone to great lengths to make its four-section boom assembly easy to service and repair. If service is required, the hydraulic sub-assembly at the rear is removable in 45 minutes.