The Gravi-Chek pump is a modernized RAM PUMP. Like the ram pump, the drive pipe for this pump is a long straight tube. The fall ratio for the drive pipe is normally about one foot of fall for every five feet of horizontal distance, or 1 to 5.

Unlike the ram pump which utilizes two "clack" valves, the operating mechanism of this pump features one valve, and a partially-bouyant ball which covers either the discharge outlet port or the waste gate. Most of the water exits through the waste gate, but a portion is forced into the accumulator.

The pressure which develops in the hydraulic accumulator can raise water over 300 feet.

Images courtesy CBG Enterprises

The water develops kinetic energy as it comes down the drive pipe (A) and exits the waste gate (C) while the ball is in the floating position.

When the exiting water obtains sufficient speed, the ball is drawn down into the ball seat, forcing water up past the discharge valve (D) and into the hydraulic accumulator or "surge tank" (E).

The system relies on air pressure in the surge tank. The Snifter Hole (F) automatically controls the air level in the surge tank by letting a little air into the system with each cycle.

Here is an exploded view of the Gravi-Chek pump mechanism.

The motorless property of this pump combined with its simple construction and short parts list make this pump particularly suitible for remote location use.

This chart shows the manufacturer's expected delivery rates for various configurations with a 2" pump.

Delivery rates go down as lift height goes up and vice-versa. The chart indicates for example that a 30 foot drive pipe with a 6 foot fall can deliver 4,000 gallons a day to a height of 20 feet, or 3,000 gallons a day to a height of 40 feet.