A stump grinder has a grinding arm that durably mounts a rotatable grinding wheel by securing the drive shaft of a motor to the grinding wheel such that a pair of bearings within the motor support one side of the grinding wheel and by supporting the other side of the grinding wheel with a stub shaft received within a third bearing. The grinding arm is laterally offset on the frame of the stump grinder to have a swing angle that is not symmetrical relative to the width of the frame, but with the swing angle starting at one side of the frame and then traversing across substantially the entire width of the frame to improve the ability of the operator to see the grinding wheel. A single joystick is movable in orthogonal directions corresponding to desired up and down and side-to-side pivoting motions of the grinding arm. The joystick includes a depressible trigger for starting and stopping the operation of the grinding wheel.

A rotating disc assembly for use on a stump grinder that can include: a rotating disc member having a peripheral edge and defining a central axis and a radial direction; a bit securing sub-assembly comprising a bit holder member mechanically connected to the rotating disc member and having a first portion extending in a first direction, and a second portion extending from said first portion along a second direction that is not parallel to said first direction; a bit mechanically connected to the bit holder member by a fastening hardware; and a first portion of the peripheral edge extending a further distance in the radial direction than a second portion of the peripheral edge; wherein the bit and the bit securing sub-assembly are sized, shaped, located and/or connected so that the first bit is at least partially shielded by a footprint of the first portion of the peripheral edge.

A wheeled chassis to which a stump grinding unit is securely attached that includes a chip collector attached to either the stump grinder or the wheeled chassis and positioned adjacent the trailing edge of the stump grinding wheel. The wheeled chassis includes a duct in fluid communication with the chip collector, and a collection bin positioned adjacent the trailing end and in spaced relation below the duct. The wheeled chassis is adapted for hitched connection to a vehicle. A blower can be positioned within the duct to produce a rearwardly directed air flow to assist in the chip movement towards the collection bin. The collection bin can be positioned on the wheeled chassis or on a vehicle to which the wheeled chassis is attached.

A cutter holder has two limbs extending at an angle to each other. A cutter is mounted on one side of the cutter holder. An opposite side of the cutter holder has a prism-shaped cavity defined thereon. The cavity has a V-shape cross-section having a recessed groove at a base of the V-shape. A center line of the recessed groove is laterally offset from a center line of the cutter holder.

A disc mulcher can be connectable to a carrier vehicle and can include a frame connectable to the skid steer, a spindle, a disc, and a variable speed motor. The spindle assembly can be connected to the frame. The disc can be connected to spindle assembly and can be rotatable relative to the frame about a central axis of the disc and the spindle assembly. The variable speed motor can be connected to the frame and can be indirectly coupled to the spindle assembly. The variable speed motor can be operable to rotate the disc.

A stump grinder has a grinding arm that durably mounts a rotatable grinding wheel by securing the drive shaft of a motor to the grinding wheel such that a pair of bearings within the motor support one side of the grinding wheel and by supporting the other side of the grinding wheel with a stub shaft received within a third bearing. The grinding arm is laterally offset on the frame of the stump grinder to have a swing angle that is not symmetrical relative to the width of the frame, but with the swing angle starting at one side of the frame and then traversing across substantially the entire width of the frame to improve the ability of the operator to see the grinding wheel. A single joystick is movable in orthogonal directions corresponding to desired up and down and side-to-side pivoting motions of the grinding arm. The joystick includes a depressible trigger for starting and stopping the operation of the grinding wheel.

A stump grinder may include a machine body and a helical rotary actuator mounted to the machine body, wherein the helical rotary actuator includes a central axis. A support may be mounted to the helical rotary actuator, and an arm may be mounted to the support. A cutting wheel may be rotatably mounted to the arm, and a motor may be operable for driving the cutting wheel. The helical rotary actuator may be configured for moving the cutting wheel along an arcuate path about the central axis.

A material reduction machine including an engine, a material reduction tool, a drivetrain, and a control system. The drivetrain is between the engine and the material reduction tool, and includes a coupling and a power transfer element, the coupling having an engaged state and a disengaged state. When engaged, the coupling enables power transfer through the power transfer element and when disengaged, the coupling inhibits power transfer through the power transfer element. The control system includes a sensor to detect a speed of the engine or the material reduction tool, a drivetrain protection system to protect the power transfer element by disengaging the coupling, and a controller to enable the drivetrain protection system based on a first signal from the sensor indicating the speed is at or above a first threshold, and to disengage the coupling based on a second signal indicating the speed is below a second threshold.

A system, for providing a rotary power to an implement of a machine, includes a first motor control valve associated with a first motor of the machine and a second motor control valve associated with a second motor of the machine. The first motor control valve is configured to be actuated at a first shift point to shift the first motor such that the first motor and the second motor switch between a first implement drive speed and a second implement drive speed. The second motor control valve is configured to be actuated at a second shift point to shift the second motor such that the first motor and the second motor switch between the second implement drive speed and a third implement drive speed. The first and second shift points are based on loading of the implement during operation. In addition, the first and second shift points are different.

A tree stump grinding wheel assembly includes a rotor having a plurality of holders distributed about its cutting periphery. Each holder has a neck in which resides a socket adapted to receive the shank of an indexable tooth. A head is attached to one end of the shank and screw threads are formed in its other end. The head has a plurality of flats configured to sequentially register with a forward shoulder on the neck. A hermetic spring is operatively disposed on the shank between a rearward face of the socket and a retention nut. The hermetic spring is made of elastomeric material and has a tapered nose that self-seats in a countersink at the rearward opening of the socket. The hermetic spring has an accordion-like bellows section. The bellows section can have a central annular bulge.