Abstract: In a riding concrete finishing trowel, a stabilizer is operatively disposed between the frame and either the gearbox or a structure that is coupled to the gearbox so as reduce the effects of rotor assembly vibration on the trowel. In one embodiment, the stabilizer takes the form of a gas spring located between the frame and the pitch control post. The stabilizer may be located relatively close to the top of the pitch control post so as to take advantage of the mechanical advantage offered by the spacing between that location and the gearbox.

Abstract: A ramming device for compacting soil includes an upper mass and a lower mass. The lower mass is driven linearly back and forth with respect to the upper mass to compact material therebelow. An engine drives the lower mass and is supported by the upper mass. A muffler is fluidly connected to the engine and is contoured such that a majority of the muffler is positioned inboard of a footprint of a side of the ramming device. Preferably, the muffler has a shape that substantially matches a shape of the upper mass adjacent to the muffler thereby further reducing the distance that the muffler extends beyond a footprint of a sidewall of the device.

Abstract: A portable vibratory screed includes a blade that is connected to a handle constructed to be manipulated by an operator. Nodes of minimum vibrational amplitude are formed at specific locations along the length of the blade when the exciter is driven at a rated operating speed. A site level and/or the handle is attached to the blade at or in the vicinity of one or more of these nodes, therefore, is relatively isolated from induced vibrations.

Abstract: A ramming device for compacting soil includes an upper mass and a lower mass. The lower mass is driven linearly back and forth with respect to the upper mass to compact material therebelow. An engine drives the lower mass and is supported by the upper mass. A muffler is fluidly connected to the engine and is contoured such that a majority of the muffler is positioned inboard of a footprint of a side of the ramming device. Preferably, the muffler has a shape that substantially matches a shape of the upper mass adjacent to the muffler thereby further reducing the distance that the muffler extends beyond a footprint of a sidewall of the device.

Abstract: In a riding concrete finishing trowel, a stabilizer is operatively disposed between the frame and either the gearbox or a structure that is coupled to the gearbox. Such a stabilizer has been found to reduce the effects of rotor assembly vibration on the trowel greater than would be expected and even to improve steering response. In one embodiment, the stabilizer takes the form of a gas spring located between the frame and the pitch control post. Preferably, this gas spring is located relatively close to the top of the pitch control post so as to take advantage of the mechanical advantage offered by the spacing between that location and the gearbox.

Abstract: A portable vibratory screed includes a blade that is connected to a handle constructed to be manipulated by an operator. Nodes of minimum vibrational amplitude are formed at specific locations along the length of the blade when the exciter is driven at a rated operating speed. A site level and/or the handle is attached to the blade at or in the vicinity of one or more of these nodes, therefore, is relatively isolated from induced vibrations.

Abstract: A method is provided of making and using a walk behind rotary trowel that is “dynamically balanced” so as to minimize the forces/torque that the operator must endure to control and guide the trowel. Characteristics that are accounted for by this method include, but are not limited to, friction, engine torque, machine center of gravity, and guide handle position. As a result, dynamic balancing and consequent force/torque reduction were found to result when the machine's center of gravity was shifted substantially relative to a typical machine's center of gravity. Dynamic balancing can be achieved most practically by reversing the orientation of the engine relative to the guide handle assembly when compared to traditional walk behind rotary trowels and shifting the engine as far as practical to the right. This shifting has been found to reduce the operational forces and torque the operator must endure by at least 50% when compared to traditional machines.

Abstract: A portable vibratory screed machine is provided with a vibration restraint operable to reduce undesirable vibration of the engine and to extend the life of the engine. The portable vibratory screed machine includes a machine frame having a reference structure. The machine further includes an engine mounted on the reference structure via a mount that surrounds a drive shaft that is driven by the engine's output. A vibratory assembly remotely located from the engine is powered by the engine to vibrate a screed plate. The vibration restraint directly couples the engine housing to the reference structure at a location that is spaced apart from the mount.

Abstract: A walk behind rotary trowel is configured to be “dynamically balanced” so as to minimize the forces/torque that the operator must endure to control and guide the trowel. Characteristics that are accounted for by this design include, but are not limited to, friction, engine torque, machine center of gravity, and guide handle position. As a result, dynamic balancing and consequent force/torque reduction were found to result when the machine's center of gravity was shifted substantially relative to a typical machine's center of gravity. Dynamic balancing can be achieved most practically by reversing the orientation of the engine relative to the guide handle assembly when compared to traditional walk behind rotary trowels and shifting the engine as far as practical to the right. This shifting has been found to reduce the operational forces and torque the operator must endure by at least 50% when compared to traditional machines.

Abstract: A vertically-extending L-shaped exhaust pipe and method of manufacturing same are disclosed. The exhaust pipe includes a drain hole located at the bottom of the horizontal portion of the exhaust pipe for allowing liquids to drain from the pipe in order to avoid harming upstream exhaust system or engine components. An elliptically shaped guide is welded into an arcuate slot immediately upstream of the drain hole and is angled in the downstream direction so as to direct the flow of liquid toward the drain opening and away from upstream exhaust system components. The present invention is simple to manufacture, eliminates the need for a noisy flapper lid, and maintains the structural integrity of the exhaust pipe.