Cantilever hold the assembly of contact wire , catenary and dropper assembly. It transfers all vertical load, lateral forces and bending moment load through insulator to Mast. It is an insulated swiveling type structural member and keeps the overhead catenary system in a position assisting smooth current collection by the pantograph at the designed speed. It is flexible with all joints having swiveling arrangement permitting movement in all direction.Material is so chosen to avoid any rusting and to last the life the OHE (35-40 years)
There are four tubes which makes the complete cantilever assembly namely
Stay Arm: It comprises of dia 28.4/33/7 mm (Small) size tube and an adjuster at the end to keep the bracket tube in position. It is insulated from the mast by stay arm insulator.
Bracket Tube: It comprises of dia 40/49 mm (Small) or dia. 30/38 mm (standard) bracket tube and insulated by bracket insulator. Catenary is supported from this member by catenary suspension brackets and catenary suspension clamp
Register Arm: It comprises of dia 28.4×33.7 mm tube to register the contract wire in the desired position with the help of steady arm
Steady Arm: It is 32 x 31 mm BFB section made of aluminum alloy to register the contact wire to the required stagger and to take the push up of contact wire. It is always in tension
Dropper is a fitting used in overhead equipment construction for supporting the contact wire from catenary. Two top tubes hold the weight; adjust the height and center of the Contact and catenary wire assembly whereas the bottom two tubes for adjusting the contact wire – stagger/height.
Contact and catenary assembly is designed for following different applications namely, push, pull, overlapping, crossover etc. The arrangement of the cantilever depends upon the height of the contact wire, encumbrance, setting distance, stagger and super elevation.
Stay and Bracket tube is supported on the mast with the help of insulator for electrical isolation called Stay Tube Insulator and Bracket Insulator. Two standard sizes of tubes 38mm and 49mm outside diameter are used for bracket assembly depending on the loading condition. Bracket assembly permits adjustment of equipment to cater for slewing or raising of track during maintenance. Length of stay tube can be varied by as much as 9 cm. in either directions and bracket tube is provided with free length of 10 cm beyond the caternary suspension clamp. Similarly projection of the register arm beyond the steady tube clamp is kept at 15 cm. This makes it possible to adjust the stagger of OHE at later stage without much difficulty.
Most important feature of Cantilever assembly is its flexibility, swiveling in all direction to take care of vertical push during movement of pantograph and expansion during change of ambient temperature and Vertical and Horizontal adjustment.