GAS AUTO TENSIONING DEVICES

THE GAS AUTO TENSIONING DEVICES CONSISTS OF THE FOLLOWING:-

A cylinder assembly, with a movable ram.

Cable tie-bar.

OHE end Cross head.

Mast side Cross head.

GAS AUTO TENSIONING DEVICES

1.Utilises Perfect GAS Principal

2.Matches Expansion Rate of GAS to that effective Contact wire length

3.Tension proportional to Gas charging Pressure.

Unlike the pulley-block type ATD’s, the Gas Tensioner does not require the use of any counter weights.

The expansion/contraction of the OHE (due to temperature variation) is transmitted to the movable ram, via the cable tie-rod.

The ram moves against pre-set pressure of Nitrogen gas inside the cylinder and thereby maintains the tensions in the overhead traction wires to the pre-determined values.

The maximum horizontal travel (stroke) of the ram will depend upon the tension length and the maximum variation in temperature.

Different models are available depending upon the maximum available stroke. Generally, the maximum available strokes are 500 mm, 900 mm, and 1250 mm.

                                                            TECHNICAL DATA

DISADVANTAGES OF GAS AUTO TENSIONING DEVICES

The main disadvantage in the case of Gas Tensioners is that their use is still not very extensive and hence the source of supply is very limited. As a consequence, the price of Gas Tensioner is, at the moment, very high, almost 4-5 times that of conventional ATD.

Another disadvantage of the Gas Tensioner is that for every Gas Tensioner, the values of installed pressure and ram-extension, have to be calculated taking into account the tension length of the OHE, where the particular Gas Tensioner is to be installed. This puts a severe restriction on interchangeability between different Gas Tensioners, which disadvantage does not exist in the case of conventional ATD’s.

RECOMMENDATIONS :

Particularly Gas ATD useful in long tunnels & elevated sections. However, its use may be resorted to only in exceptional cases, since its cost is high.