What is a HVSS Suspension?

In this brief article, we will discuss the HVSS tank suspension, its layout and its advantages.

What is a HVSS Suspension?

The horizontal Volute Spring Suspension (HVSS) was a suspension system used on the Sherman Tanks in the later part of World War II and also post World War II. It was used on the Sherman M4A3 and the M4A4.

The HVSS was evolved out of the problems faced with the earlier VVSS (Vertical Volute SPring Suspension) that was earlier used on Sherman tank Chassis’. The VVSS system limited the Sherman tank’s articulation abilities due to the limited vertical wheel travel that often caused an “Axle Floatation” problem, leading to loss of grip while climbing.

It consists of a Boggie arrangement within the Sherman Tank’s Tracked wheel traction system. The tracks of the tanks would be pressed down against the terrain using this HVSS boggie arrangement.

A Volute Spring is a conical spring made of coiled sheet metal strip that can collapse to the minimum height equal to the width of the sheet metal strip. A Helical spring, on the other hand, could collapse only down to the height equal to the thickness of all the coils stacked vertically. Thus, the Volute spring provided for greater travel.

The HVSS suspension’s basic architecture involves a Boggie wheel arrangement. The tandem arrangement and the articulation between the wheels is through a Torsion bar and the Horizontally mounted Volute Spring. When one wheel in the Boggie articulates, the track bar transfers the load to the other boggie wheel through the 2 horizontal torsion bars as well as the horizontal volute springs. The Boggies suspension had a hydraulic shock absorber mounted in coilover fashion concentric to the Horizontal volute spring.

What are the advantages of the HVSS Suspension?

  • Improved wider Track:

The HVSS layout was such that it allowed an additional set of wheels, one set on either side of the HVSS chassis support bracket. This allowed an increase in the track width (23 inches) and thus better grip.

  • Better Articulation: 

The Horizontal Spring arrangement was an improvement over the previous version VVSS (Vertical Volute Spring suspension) in that it allowed more room above the wheels. The wheels were also now larger as the packaging space had expanded. The Horizontal spring allowed for more vertical wheel travel.

Conclusion

In this brief article, we have discussed the HVSS tank suspension, its layout and its advantages.

In case of any questions or queries, please feel free to ask.

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