The cam is actuated by a user by rotating the handle, causing a cam to lift the weight and let it fall freely on the frame attached to the ram head.  This produces a standard compacting action to a pre-measured amount of sand. Demonstration of this apparatus can be seen here: 
Variety of standard specimen for Green Sand and Silicate based (CO)sand are prepared using a sand rammer along with accessories
The object for producing the standard cylindrical specimen is to have the specimen become 2 inches high (plus or minus 1/32 inch) with three rams of the machine. After the specimen has been prepared inside the specimen tube, the specimen can be used for various standard sand tests such as the permeability test, the green sand compression test, the shear test, or other standard foundry tests.
The sand rammer machine can be used to measure compactability of prepared sand by filling the specimen tube with prepared sand so that it is level with the top of the tube. The tube is then placed under the ram head in the shallow cup and rammed three times. Compactability in percentage is then calculated from the resultant height of the sand inside the specimen tube.
A rammer is mounted on a base block on a solid foundation, which provides vibration damping to ensure consistent ramming.