Skyjack LEEDs the Way
Green construction projects and jobsites with environmental concerns provide the perfect home for the SJ 8831E scissor lift.
By Guy Ramsey and Katie Parrish
Editor’s Note: The construction market is gravitating toward electric rough-terrain aerial work platforms because they reduce noise pollution and emissions and improve fuel costs. Battery-powered electric scissors seemingly fulfill that need, and Guelph, Ontario-based Skyjack brought its versions of their DC electric scissor lifts—the SJ 8831E—to the 2009 Lift and Access Equipment Showcase.
January 27, 2010 – When Lift and Access decided to offer a Manufacturer’s Choice category for aerial work platforms at the 2009 Equipment Showcase, Paul Kreutzwiser, senior product marketing manager, said it didn’t take long for Skyjack to decide to bring the SJ 8831E rough-terrain electric scissor lift to the event. “I don’t get a chance to show these off too much,” he said.
Although a niche machine, the company extends its design philosophy—including keeping its machines simple and robust and its components common throughout its product lines—to the SJ 8831E.
The SJ 8831E is an axle-based, electric-drive scissor lift and uses the same axles, scissor stack, and platform as the engine-powered version of this model. Naturally, the key difference is the 48-volt direct electric drive, and the eight 6-volt batteries located on the slide-out tray that would normally house the engine. For the direct electric drive, a 14-hp electric motor is attached to a gear box, which is then connected to the front and rear axle. The rear axle is a Detroit Locker locking differential, the same as the IC version, and the front steering axle is a Dana clutch-type limited slip. Although it employs the hard-wired relay logic design with numbered and color-coded wiring that is common to all other Skyjack models, the company makes a minor departure by incorporating a Sevcon motor controller on the SJ 8831E. The Equipment Showcase model featured four-wheel drive, but two-wheel drive is also available.
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In place of a hydraulic motor, the 14-hp DC motor drives the transfer case.
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Two electric motor pump systems provide power for system functions. The 14-hp motor not only provides drive, but it also supplies power for the hydraulic lift function. A 4-hp motor-gear pump combination performs steering and braking functions. A tach-gen on the end of the electric drive motor provides constant speed feedback to the Sevcon motor controller, enabling infinite proportionality.
Steel lockable cabinets located on the side of the machine house the hydraulic tank and two 48-volt chargers. While only one charger is required, the SJ 8831E’s charge time is cut in half when both are used together—a dead machine can be brought to full charge in about five hours. If only one charger or outlet is available, charge time is about 10 to 12 hours. Skyjack notes the scissor lift has no problem getting through a full eight-hour day once the batteries are fully charged.
For operator comfort, twin lift cylinders are placed wide apart to provide a more stable platform. Skyjack’s signature welded-in-place, cast clevis-style scissor ends are also used. The scissor stack is attached so that as the platform is elevated, the slide blocks at the top and on the chassis are pulled to the center. Skyjack notes that with the stack in the center of the frame and deck, it provides a rigid feeling and adds platform capacity and stability.
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The slide-out battery tray houses the unit’s eight 6-volt batteries.
| The Showcase SJ 8831E featured a single 4-foot roll-out deck extension and offered 2,000 pounds of lift capacity. Units without any deck extensions have 2,500 pounds of capacity, while the double extension deck versions provide 19 feet of platform length and 1,500 pounds of capacity. When stowed, the all-steel diamond plate deck is 5'8" wide and 12 feet long.
The SJ 8831E’s lower controls are not 100 percent common with other Skyjack products because of the unique use of the motor controller, but the upper controller, including the control box and switches/buttons, are all standard Skyjack. The aluminum constructed box can be easily taken apart for service. It is removable for safe storage or repair and can be plugged in at the side of the base to control the unit. This allows for troubleshooting the control cables that run up the scissor arms. If the controller works from the chassis but not the platform, the issue is in the wiring.
Stated drive speed on the machine is about 3 mph, and it provides 30 percent gradeability. Tilt is 2.5° side-to-side and 4.5° fore-and-aft. Driving while elevated more than 10 feet will decrease the drive speed, but the direct electric drive offers maximum torque at any speed.
The 10x16.5 skid-steer-type tire is standard, and foam-filled, non-marking, and floatation tires are options. Other accessories include pipe racks, work lights, and automatic self-leveling outriggers.
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