Abstract: A jack as provided for use with a lifting device having two parallel support platforms. The jack has base and top elements, and a scissor mechanism between them. Two air piston and cylinder assemblies are disposed vertically and actuate the scissor mechanism. The jack is mounted for free movement along the length of a lifting device. The piston and cylinder assemblies can be connected to mid points of the arms of the scissor mechanism on either side of it. This provides a compact assembly with the piston and cylinder assemblies working at an optimum angle. The base element of the jack includes openings for the piston and cylinder assemblies.

Abstract: A lifting device, for vehicles, has two support platforms. Scissor mechanisms connect these platforms, to bases, and are actuated by hydraulic piston and cylinder assemblies. A combiner and divider valve supplies fluid to the two hydraulic cylinders. A single cross brace can be provided between the two support platforms. This ensures the two platforms operate uniformly, even for an uneven load distribution, while giving a clear working space.

Abstract: A jack is provided for use with a lifting device having two parallel support platforms. The jack has base and top elements, and a scissor mechanism between them. At least one air piston and cylinder assembly actuates the scissor mechanism. To ensure that the jack can be freely moved along the length of a lifting device, a plurality of horizontal rollers and a plurality of vertical rollers are provided. The horizontal rollers are mounted by spring biasing means, so that, when a vehicle weight is taken by the jack, the spring means is compressed. The jack then contacts the support platforms, to prevent further movement of it. The jack can also include two vertical air piston and cylinder assemblies, which are connected on either side of the scissor mechanism.