Skyjack booms get bigger
By Maria Hadlow06 May 2009
Intermat saw the latest in Skyjack's growing range of rough terrain articulating booms. The SJ51AJ offers a 15.58 m (51 ft) platform height 9.16 m (30 ft) outreach and a 7.63 m (25 ft) up-and-over height. It's most notable characteristics include continuous 3600 turret rotation, true vertical rise, direction sensing controls and the "Detroit-locker" style drive system.
With 3600 continual rotation and zero tail swing, the SJ51AJ is able to manoeuvre through constricted work sites. The vertical rise mechanism ,which also features on the smaller SJ46AJ, enables the user to send the basket straight up or down without having to readjust for the boom or the jib. This was clearly demonstrated at the show on a huge TV screen showing the basket rising smoothly, parallel to vertical walls with a single command.
Another intuitive control is achieved by direction sensing: simply, this means that forward on the boom is the direction in which the operator is facing. The boom senses where the operator has rotated the boom to and over 900 from parallel it changes "forward" to the opposite direction. The advantage is that the operator doesn't have to double check the arrows on the machine base to establish which way he's about to go.
Skyjack admits that its use of a "Detroit -locker" type drive system increases the cost of manufacturing the booms, but says that the cost is not passed to customers. The company is confident that its chosen drive system is superior to others and that the performance of the machines in variety of difficult terrains - including mud, snow and sand - proves its value.
The Detroit -locker is a positive lock differential drive system, it maximises traction by delivering 100% of the torque to both drive wheels. It is designed to keep both wheels in constant drive-mode so if one wheel loses contact with the ground or encounters slippery conditions traction is maintained. The Detroit -locker system can be said to reduce manoeuvrability: to overcome this Skyjack's machines allow the operator to unlock the rear differential which improves turning radius and reduces tyre marks on hard surfaces.
The design of the SJ51AJ is sympathetic to maintenance and repair work. The swing-out engine gives comfortable accessibility to all areas, wiring is standard across all Skyjack machines for ease of servicing and machines for the European market have a battery condition indicator.
A recessed control panel helps prevent it being damaged and the fuel tank is obvious and easy to fill - in contrast to hydraulic tank - so refuelling mistakes in the field (apparently a huge problem for rental companies) cannot easily be made.
Skyjack's SJ46AJ 14.15 m (46 ft) articulated boom was launched at Apex last September a new 14 m (46 ft) with no jib has not yet been shown and the company expects to launch an 18 m (60ft) articulated boom some time next year.