Abstract: A sod harvester can employ a roll forming mechanism that includes a roll starter that is configured to initiate the formation of rolls. The roll starter can include pivoting supports and front and rear slab flippers that also pivot to cause the rolls to be tightly and consistently formed. The roll forming mechanism can also include a roll advancer that continues the formation of the rolls. The roll advancer can be suspended to cause it to conform to the shape and size of the rolls as they advance.

Abstract: A torque balancing scheme for a velocity controlled drive system of a mower is provided. The torque balancing scheme can be employed on any mower or other similar vehicle having a drive system in which a separate motor is used to independently drive each wheel. By implementing the torque balancing scheme, a drive system can prevent excessive heating of the motors that may otherwise occur when unaccounted-for factors exist.

Abstract: A mower deck can include a rocker suspension that enables a more uniform cut even when the ground is bumpy. The rocker suspension can include opposing rocker members that are coupled to a support assembly via a pivot point. The opposing rocker members can support front and rear rollers or other rolling mechanisms. When the front or rear rollers encounter a bump, the rocker members can rotate around the pivot point to minimize the vertical displacement of a cutting unit. The front and/or rear rollers may be part of a roller assembly that forms a secondary rocker suspension.

Abstract: A mower deck can include a suspension that allows a rear roller to pivot rearwardly and upwardly when the rear roller encounters a bump in the ground. The suspension can include brackets having a front end that is coupled to a housing of the mower deck at a pivot point. The rear roller can be coupled between rear ends of the brackets. Springs can be used to bias the brackets into a maximum angle of less than 90 degrees to the horizontal.

Abstract: Techniques are provided for path-based mower deck lifting. A mower can include a control system that is configured to receive path data defining a path that the mower should traverse to cut an area of grass. The path data can include lift instructions that define where within the path the mower decks should be lifted. The control system can use the path data to cause the mower to traverse the path and to predictively cause the mower decks to be lifted at the defined locations within the path.

Abstract: A cutting unit for a mower can include blades and separate lifting devices to cause grass to stand up before being cut by the blades. The cutting unit can include disks to which the blades and lifting devices are secured. The lifting devices can be positioned rotationally in front of the blades.

Abstract: An automatic feed system for a trimmer is provided. Such trimmers include a line that can be spun at high speeds to cut vegetation along roadsides or other areas. The automatic feed system is configured to dynamically detect the current length of the line and automatically feed the line to maintain a maximum or desired length for cutting. This length may typically correspond with the radius of a trimmer deck in which the line spins.

Abstract: A steering system for a mower can include a wheel-specific driving unit for each wheel and a controller for providing control signals to each wheel-specific driving unit to thereby cause each wheel to be independently rotated at a different speed during a turn. By independently rotating each wheel, the mower can complete a turn without damaging the grass. The controller may also provide control signals to cause each steerable wheel to be positioned in a different wheel direction during the turn.

Abstract: A roll forming mechanism can include a passive roll-up mechanism that initiates the roll and an active roll-up mechanism that completes the roll. The active roll-up mechanism can include an upper conveyor that is rotated in different directions. The upper conveyor can initially be rotated in a direction opposite that of an inclined conveyor to cause a forming roll to advance along the inclined conveyor. The rotation of the upper conveyor can then be reversed to cause the roll to be completed. Then, the upper conveyor can again be rotated in the direction opposite that of the inclined conveyor to cause the completed roll to be transferred towards the stacking conveyor. The amount by which the upper conveyor is rotated in the reverse direction can be based on a detected length of a tail of the forming roll.

Abstract: Synchronizing variables can be tuned based on a sod harvester's speed. A sod harvester's control system can include a tuning component that receives as input a current speed of the sod harvester. The tuning component can apply logic to the current speed to calculate values for synchronizing variables that are tuned for the current speed. In this way, the sod harvester can be operated with precision across a range of speeds, including at high speeds.

Abstract: A steering system for a mower can include a wheel-specific driving unit for each wheel and a controller for providing control signals to each wheel-specific driving unit to thereby cause each wheel to be independently rotated at a different speed during a turn. By independently rotating each wheel, the mower can complete a turn without damaging the grass. The controller may also provide control signals to cause each steerable wheel to be positioned in a different wheel direction during the turn.

Abstract: A sod harvester's stacking position can be dynamically adjusted to form vertically aligned stacks. More particularly, a sod harvester's control system can be configured to automatically adjust the stacking position as a stack is being formed based on a sensed orientation of the pallet. In this way, the control system can ensure that a slab of sod that is dropped from the stacking head will fall into the intended location on the stack regardless of the orientation of the pallet relative to the stacking head.

Abstract: A mower can dynamically adjust the cutting height of a mower deck based on a mower's location. As a mower travels over an area of grass to be cut, a control system can track the current location of each mower deck on the mower. The control system can compare the current location of a mower deck to a boundary of one or more sections defined within the area to thereby determine which section the mower deck is within. When the control system detects that a mower deck has crossed or will cross into a section, it can identify a particular cutting height assigned to the section and dynamically adjust the cutting height of the mower deck to the particular cutting height. When a mower includes more than one mower deck, the control system can be configured to independently adjust the cutting height of each mower deck based on its location.

Abstract: A sod harvester's stacking position can be dynamically adjusted to form vertically aligned stacks. More particularly, a sod harvester's control system can be configured to automatically adjust the stacking position as a stack is being formed based on a sensed orientation of the pallet. In this way, the control system can ensure that a slab of sod that is dropped from the stacking head will fall into the intended location on the stack regardless of the orientation of the pallet relative to the stacking head.

Abstract: A stacking head for stacking rolls of sod can include a number of screw assemblies that are employed to secure and remove sod rolls from a stacking conveyor. Each screw assembly can include a center stake and a corkscrew that pierce a roll as the stacking head is forced into the roll. The rate at which the stacking head is moved vertically relative to the roll can be synchronized with the rate at which each screw assembly is rotated. This synchronization ensures that the corkscrew will pass into the roll while the stacking head is simultaneously forced into the roll without damaging the delicate sod.

Abstract: Synchronizing variables can be tuned based on a sod harvester's speed. A sod harvester's control system can include a tuning component that receives as input a current speed of the sod harvester. The tuning component can apply logic to the current speed to calculate values for synchronizing variables that are tuned for the current speed. In this way, the sod harvester can be operated with precision across a range of speeds, including at high speeds.

Abstract: A cutting head for a sod harvester is configured to counterbalance forces that are generated during operation. When the cutting head is operated, the cutting blade oscillates to sever sod from the ground. This oscillation of the cutting blade generates significant horizontal vibration forces that are transferred to the cutting head and other components of the sod harvester. The cutting head can include a crankshaft assembly with counterweights that are designed to balance these horizontal vibration forces. The cutting head can also include a countershaft assembly with counterweights that are also designed to balance these horizontal vibration forces while also balancing vertical vibration forces that the counterweights of the crankshaft assembly create.

Abstract: A sod harvester can employ a roll forming mechanism that includes a roll starter that is configured to initiate the formation of rolls. The roll starter can include pivoting supports and front and rear slab flippers that also pivot to cause the rolls to be tightly and consistently formed. The roll forming mechanism can also include a roll advancer that continues the formation of the rolls. The roll advancer can be suspended to cause it to conform to the shape and size of the rolls as they advance.

Abstract: Sod harvesters are configured to stack rolls of sod in layers on a rectangular pallet. A sod harvester can include control circuitry that is configured to operate a stacking head and a stacking conveyor in a manner that produces a first type of layer that includes spaced groups of accumulated rolls and a number of offset rolls positioned between the groups. The stacking head can pick up and stack each offset roll in isolation and may pick up the offset rolls in a center position of the stacking head.

Abstract: Sod harvesters are configured to stack rolls of sod in layers on a rectangular pallet. A sod harvester can include control circuitry that is configured to operate a stacking head and a stacking conveyor in a manner that produces a first type of layer that includes spaced groups of accumulated rolls and a number of offset rolls positioned between the groups. The stacking head can pick up and stack each offset roll in isolation and may pick up the offset rolls in a center position of the stacking head.