Heavy Duty Assisted Lift Trunnion Operation and Maintenance Manual
Form Reference
C64.65546
Issue
5.00
10 of 39
Issue Date
May 2021
Description
The Unipart Dorman HD ALT is a device designed for use in the railway environment as a
means of erecting a signal and then forming the support structure for that signal. It is
constructed of two main sub-assemblies. The base plate, designed to suit a BRS-SC-45 footprint
and a tubular housing with two spring units attached connected by a main hinge. The main
tubular housing has a signal securing collar and electrical connection box as constituent parts.
The two sub-assemblies share mountings for the hold down pin and brackets. Lifting eyes are
provided for ease of transport and installation.
Once the signal head and post are inserted and the HD ALT is in its vertical position the two
sub-assemblies are secured together using 8 x M24 bolts and this action forms the main
mounting interface between the signal and the foundation.
When vertical, all spring force is dispersed and there is no stored energy in the unit.
Signal Configuration and Lifting Data
The HD ALT system will support a wide range of Unipart Dorman signal heads as shown in
Unipart Dorman drawing 0094/019441 which is available on the Unipart Dorman website.
The complete signal is available at varying heights as measured from the top of the railhead to
the centre of the most restrictive aspect and a further dimension from the top of the rail to the
top of the foundation. This data and the precise geographic location information is supplied by
the customer against a unique signal identifier.