Gravity Ram - Design

THE GRAVITY RAM

Design Details

A Simple Device to Generate Power from the Tides
The Gravity Ram is composed of a float, a piston and a cylinder. The float is connected to the piston and the piston is fitted into the cylinder. The float goes up and down on the tide driving the piston up and down in the cylinder. The pressure caused by the volume of water flowing into and out of the cylinder provides motive power to drive a generator.

General Arrangement
The Gravity Ram at Low Water
The Gravity Ram at High Water
The Pressure Seal Arrangement
Production
Installation Details

General Arrangement

Key

1
2
3
4
5
6
7
8

Cupola
Piston
Seal
Seal Gutter
Inlet/Outlet Valve
Inspection Hatch
Cylinder
Shroud

Notes

The float assembly is enclosed in the shroud, (8) which forms the flotation chamber of the piston and gives it yet more stability.
The key to the operation of the gravity ram lies in the seal, (3) between the piston and the cylinder walls. I've developed a new type of pressure seal to accommodate the often very substantial pressures involved, and also the movement of the assembly Pressure Seal
Details of the seal will be supplied on acceptance of any project involving the gravity ram.
Inquiries

Gravity Ram at Low Water

Showing the Gravity Ram at the start of the operating cycle. As the tide rises, sea water enters through the inlet/outlet valve and raises the piston assembly

Gravity Ram at High Water

At high tide, the piston assembly has reached the top of its stroke and is ready to deliver power to the generator. The inlet/outlet valve changes to the outlet position, and water flows under pressure to the turbine or other device.

Pressure Seal Arrangement

The bottom of the piston should be slightly domed to allow space for the pressure to build up, also to trap any air that may be sucked into the device (this increases buoyancy).
A hard plastic or flexible metal seal should then be fitted into the dome extending from it down into a "gutter" let into the base of the cylinder (around the edge). To achieve a perfect or really good seal a slightly cone-shaped diaphragm is needed.
Water then drawn into the cylinder bears on the diaphragm forcing it against the cylinder wall. The higher the pressure the stronger the seal. The seals wear out in time but can be easily replaced by jamming the ram at the top of its cycle and accessing the cylinder through a service hatch let into the side of ihe cylinder or into the top of the piston. These service hatches can be made self-sealing by being constructed in a conical shape and supplied with simple rubber or plastic grommets.

Key

3
4
6
10

Pressure Seal
Gutter to Receive Seal
Self Sealing Inspection Hatch
Concave Face of Piston and Seal

Production

Gravity rams can be produced to suit a variety of locations/situations and can also be configured to work on dry land provided only that there is a supply of water. In this configuration they provide excellent high pressure pumps for lifting water vertically or for providing motive power for hydraulic systems. Gravity rams need very little maintenance over long periods of time and are cheap to construct.

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