Heavy Duty Assisted Lift Trunnion Operation and Maintenance Manual
Form Reference
C64.65546
Issue
5.00
4 of 39
Issue Date
May 2021
Introduction
The Unipart Dorman Heavy Duty Assisted Lift Trunnion (HD ALT) uses twin reactive springs
controlled by a fulcrum system that allows the force required to move the signal post from the
horizontal to vertical to be equalised across the full range of movement. This means that it can
be raised and lowered by hand without any additional mechanical handling equipment.
HD ALT is designed to interface with only Unipart Dorman Lightweight and CLS LITE Signals as
shown in the product configuration drawing C64.65378. Additionally, the HD ALT can be used
to mount a variety of Classic Signals & Indicators and level crossing Road Traffic Lights
(Wigwags) using the brackets detailed in the Network Rail Product Acceptance Certificate
PA05/06503.
A separate document will cover the Offset post when used in HD ALT
The complete signal can be quickly installed onto a standard foundation or screw pile system
set with 4 x M24 studs at 380mm centres as shown in Network Rail Drawing BRS-C-45. These
studs should have a MINIMUM of 200mm threaded section available above the top face of the
foundation.
Although the HD ALT was developed from and shares many similarities with the Standard ALT,
they are entirely separate products with distinctive operation and safety properties. Any
acquired knowledge of the Standard ALT shall not be used as a cross reference to the HD ALT.
Separate O&M Manuals and Product Awareness Sessions are available for both Trunnions and
these are available from Unipart Dorman.
