The bottle jack consists of a hydraulic unit on a base-plate.
These jacks may have single rams or double telescoping rams, and are made in various sizes.
A single acting pump is used to raise the jack ram.
A release valve is fitted, which when opened, allows fluid in the cylinder to return to the reservoir. This allows the ram to descend. Bottle jacks are used mainly for raising individual undercarriage legs in order to change wheels and brake units etc.
They may be used on their own or in conjunction with an adapter or swan-neck, which is attached to the undercarriage leg or boogie beam.
