Guelph, Ontario-based, Skyjack's SJ 45T and jib-less SJ 40T were designed with reliability and easy service in mind. To meet these objectives, the company relies on robust and unique components.
For example, the use of a differential drive is unique to Skyjack. The steering axle is supplied by Dana Spicer and features limited slip, while the drive axle has a locking differential. Both are individually rated at 18,000 pounds capacity. Skyjack believes these axles offer superior traction and are more robust than conventional hydraulic-drive axles. The drive train is powered by a single Sauer-Danfoss model KV38 two-speed hydraulic motor. Additionally, the SJ 45T at the Boom Lift Showcase was fitted with the optional oscillating steer axle.
Powering the SJ 45T is the standard 48-horsepower Deutz F3L-2011 oil-cooled engine; a GM Vortec 3-liter gas engine is available as an option. The Deutz model comes with a microprocessor-based management control system that monitors emission standards and provides engine status flash codes.
The main lift cylinder is trunnion-mounted, which means the pins are captured with a collar that is bolted into place. The cylinder pins can be removed with a wrench, rather than a sledgehammer. To facilitate lubricating the axles, a central grease bulkhead has been provided at the rear of the boom.
Skyjack sticks with its analog control system as much as possible, which typically means more wires, compared with machines that utilize a computer with digital communication capabilities. To keep the wires straight, Skyjack uses its standardized number-and-color-coded wiring system.
A microprocessor in the upper controls is required to limit the number of wires required in the boom to support a relay-based system. Skyjack turned to the proven OEM Controls OCM1-Control Module. The size of a single cable required to support an analog-based system, however, would be too large and possibly too stiff to work properly in the power track, so Skyjack incorporated a pair of smaller cables to make it easier to troubleshoot and cheaper to replace. Smaller cables also are less likely to coil.
The utilization of a proven product like Fairfield Manufacturing's slewing drive with an integral brake package is another great feature on the SJ 45T. The same goes for the 180-degree Helac basket-rotation actuator, which is bolted to an independent bracket to facilitate removal.
On the platform, the guardrails are modular and bolted together. If a piece is damaged, the owner can simply remove it for repair or replacement. The standard 36-x96-inch platform utilizes side-swing gate access. Unrestricted capacity is 500 pounds on the SJ 45T and 650 pounds on the SJ 40T.
Supports underneath the platform floor form a gradual V-shape to make the center higher. This is designed to take the brunt of abuse when the platforms are lowered or slammed onto the ground. The floor is constructed of expanded metal.
Controls are conventional and straightforward. The right-hand single-axis joystick, supplied by OEM Controls, is a non-contact Hall-effect design that utilizes a thumb rocker to control steering. The left-hand dual-axis joystick operates the lift and rotation functions. A directional-sensing drive system passively orientates the drive so the machine is always moving in the direction consistent with the joystick's input no matter the position of the superstructure.
The SJ 45T was the heaviest machine at the event (16,195 pounds). Its steel makeup, differential drive, and robust power track translate into a lot of extra weight. But I'm sure that being the lightest machine on the market was never one of the key design parameters.
