Abstract: Sod harvesters can have hydraulic systems that are configured to actuate components with precise timing. The hydraulic system of a sod harvester can be configured to maintain the temperature of hydraulic fluid both during harvesting and while harvesting is paused to thereby eliminate or minimize the occurrence of periods of variation in the timing of actuation of the components that the hydraulic fluid drives. As a result, these components can be consistently actuated with precise timing even after harvesting has been paused. Additionally, such configurations can minimize the amount of time required to warm the hydraulic fluid to a steady operational temperature.

Abstract: In a winged agricultural implement having two wing frame sections pivotal relative to a center frame section between a laterally extending working position and a rearward trailing transport position, two brace members are pivotally supported on the center frame section to selectively retain and support the wing frame sections in the working position. A hydraulic actuator pivots each brace member between a latched position and a released position relative to the wing frame section. A biasing linkage is provided in series with each hydraulic actuator to provide positive pressure to retain the brace member in a latched position as the wing frame section pivotally floats relative to the center frame section during movement across an agricultural field in a forward working direction.

Abstract: A power hitch relief system for a three-point hitch used in tractors and similar vehicles. The power hitch relief system includes an inclination detector in the form of a weight pivotally mounted to the tractor frame. The weight is also coupled to a relief valve of a hydraulic circuit which supplies power to the hitch. The weight pivots when the tractor pitches backwardly to open the relief valve and relieve fluid pressure in the hydraulic circuit. This prevents the tractor from overturning backwardly. A catch keeps the relief valve open to prevent oscillations until reset.

Abstract: A tractor has an engine, a torque converter, a lifting device for attachment to an implement such as a plow, the torque converter being controlled automatically whereby if an engine-driven ground wheel starts slipping, the torque converter reduces the tractor's speed. Engine speed and the implement's depth of penetration are also automatically controlled in dependence on the retarding force caused by the implement. In another embodiment, a power take-off shaft is automatically disengaged if the retarding force becomes excessive.