Sod harvester chop mechanism having position based speed control

A chop mechanism for a sod harvester comprising:

• a fixed frame;
• a chop frame that is configured to move within the fixed frame, the chop frame including a blade that inserts into the ground as the chop frame moves within the fixed frame;
• a follower secured to the chop frame;
• a cam positioned to contact the follower as the cam is rotated thereby lifting the chop frame, the cam including a flat edge which causes the follower to be dropped when the cam is rotated to a drop position;
• an electric motor for rotating the cam;
• and
• a control unit configured to output control signals for controlling the rotation of the electric motor based on a position of the cam.

A method performed by a control unit of a sod harvester for controlling the rotation of a cam during a chopping action, the method comprising:

• receiving a first signal indicative of the cam being in a ready position;
• receiving a second signal indicative of a ground position of the sod harvester;
• generating a first control signal for controlling a motor used to drive the cam, the first control signal causing the motor to rotate the cam through a drop position in which a follower is dropped by the cam to a safe position in which the follower will not strike the cam as the follower drops;
• and
• generating a second control signal for controlling the motor, the second control signal causing the motor to rotate the cam from the safe position to the ready position.