The PM-55 is a version of standard Warsaw Pact MT-55 bridging system. The bridge is normally carried on a T-55 tank chassis, but the PM-55 uses a variant of the Tatra 813 cross-country truck that could carry and deploy the bridge.
Wikipedia has a
short article about the MT-55. A Czech forum has an extensive
collection of photographs of the bridge-laying truck in action.
This item consists of a truck deploying the bridge. A set of
two trucks carrying the bridges and two deployed bridges is also available.
A
forum entry on The Miniatures Page mentions this model.
Other Warsaw Pact engineering equipment can be found at
Luke Ueda Sarson's shop