Hydraulic float down valve for a camera dolly or camera crane

A camera dolly or camera crane, comprising:

• an arm supported on a chassis;
• a hydraulic cylinder pivotally attached to the arm and to the chassis;
• a valve linked to the hydraulic cylinder and to a pressurized hydraulic fluid source, with the valve including a valve body containing a first spring biasing a first pin into engagement with a first seat, and a second spring biasing a second pin into engagement with a second seat, and a swash plate supported on the valve body to selectively move the first and second pins;
• a cam or a nut movable from a first position wherein the first and second pins can seal against the first and second seats, respectively, to a second position wherein the cam or nut displaces the swash plate and holds the first and second pins apart from the first and second seats, respectively.

A camera dolly, comprising:

• an arm supported on a chassis;
• a hydraulic cylinder linked to the arm;
• a valve connected via hydraulic lines to the hydraulic cylinder and to a pressurized hydraulic fluid source, with the valve shiftable from a normal mode of operation to a float-down mode of operation, and vice versa, and the valve including a first pin moveable via a valve plate to make or break a first seal with a first seat, and a second pin moveable via the valve plate to make or break a second seal with a second seat, when the valve is in the normal mode of operation;
• a cam or a nut movable from a normal position wherein the cam or nut does not substantially displace the valve plate and both the first and second pins can seal against the first and second seats, respectively, for normal valve operation, to a float-down position wherein the cam or nut displaces the valve plate and holds the first and/or second pins apart from the first and second seats, respectively, for float down valve operation, wherein the arm rises to a peak height and then automatically descends.