Spierings » SK387-AT3 City Boy
The basic principles of this new crane concept fully differ from that which has been produced by Spierings so far. The name of the model is SK387-AT3 City Boy and the main purpose - city contructions. From this set of requirements, the most noticeable is the single crane operator's cab, that also serves as driver's cab, as crane cab and as lift to reach the top of the tower for optimal view of the crane operator in every operating situation. Additional requirements were: more hook height by adding a third tower section, a maximum truck width of 2.5 mtrs and the possibility to luff up to 45˚. The truck's main drive unit of the City Boy is a very compact electric motor of max. 400kW (540hp), which is directly coupled to the front cardan shaft without the intervention of gearbox and/or transfer case. A frequency control will convert accelerator pedal operation into a continuously variable acceleration of the truck from 0 to 80 km/h. The same electric motor serves a an electric brake when you want to slow down, e.g. for traffic lights. The energy necessary to move the truck is provided by a small diesel engine, running at a constant speed, with a generator that converts the energy from diesel to electric energy very efficiently. The peak capacity to accelerate and/or drive up-hill is supplied by a powerful lithium-ion-battery. When the vehicles brakes or runs down-hill, the energy is returned to this battery. Besides the electric main drive the truck is also fitted with a hydraulic auxiliary drive on the rear cardan shaft, to improve the terrain accessibility on the work area. The energy needed for this auxiliary drive is supplied by the hoisting winch pump. Also when the tower is in upright position and the all-in-one cab has been converted to crane cab, the truck may be driven. Steering, acceleration and braking are carried out using the crane's remote control. To give the crane operator an optimal view while driving in heavy traffic as well as while operating the crane, the crane is rotated 180˚ on the truck compared to other Spierings cranes, creating a free space between tower and jib. In order to keep the usual truck feeling, the all-in-one cab is mounted at the front of the tower.