Abstract: Methods and apparatus for power finishing freshly placed concrete in which the acoustic impedance of the treating equipment is made substantially equal to the acoustic impedance of the concrete slab being treated. Preferably, a powered, twin rotor riding trowel is provided with a pair of circular finishing pans that are attached to the conventional rotor blades used later in the finishing process. The pans are characterized by an acoustic impedance approximating the acoustic impedance of green concrete, thereby optimizing the energy transferred to the concrete. Preferred pans comprise ultra-high molecular weight polyethylene (UHMWPE) plastic. During troweling, the pans are frictionally revolved over the green concrete for finishing the surface without prematurely sealing the uppermost slab surface. Through the disclosed troweling method, a highly stable concrete surface results, and delamination is minimized. Alternative troweling uses pans coated with layered impedance matching material.

Abstract: High performance, multiple rotor riding trowels for finishing concrete comprise hydraulic circuitry enabling complete joystick control to the operator. The rigid trowel frame mounts separate spaced-apart, downwardly-projecting, bladed rotor assemblies that frictionally engage the concrete surface. The rotor assembly blades finish the surface while supporting the trowel. The rotor assemblies are tilted with double acting, hydraulic cylinders to effectuate steering and control. Double acting hydraulic cylinders also control blade pitch. Separate gimbaled, hydraulic motors revolve each rotor assembly. A joystick system enables operator hand control with minimal physical exertion. The joystick system activates electrical circuitry that fires solenoid control valves to energize various hydraulic cylinders that tilt the rotors and alter blade pitch. The hydraulic steering control circuit driven by a motor driven pump pressures a flow divider circuit to control the solenoid tilt control valves.

Abstract: A high performance, twin rotor riding trowel for finishing concrete and hydraulic circuitry therefor, enabling complete joystick control to the operator. The rigid trowel frame mounts two spaced-apart, downwardly-projecting, bladed rotor assemblies that frictionally engage the concrete surface. The rotor assembly blades finish the surface while supporting the trowel. The rotor assemblies are tilted with double acting, hydraulic cylinders to effectuate steering and control. Double acting hydraulic cylinders also control blade pitch. A joystick system enables the operator to hand control the trowel with minimal physical exertion. The joystick system activates electrical circuitry that fires solenoid control valves that in turn energize the various hydraulic cylinders that tilt the rotors and alter blade pitch. The hydraulic control circuitry comprises a motor driven pump delivering pressure to a flow divider circuit.

Abstract: A high performance, hydraulically-propelled, multiple rotor riding trowel for finishing concrete is controlled with hydraulic circuitry enabling steering wheel and foot pedal control. The rigid trowel frame preferably mounts three separate spaced-apart, downwardly-projecting, bladed rotor assemblies that frictionally engage the concrete surface. The rear rotor assemblies are tilted with double acting, hydraulic cylinders to effectuate steering and control in response to foot pedals. Double acting hydraulic cylinders also control blade pitch. Separate gimbaled, hydraulic motors revolve each rotor assembly. A steering wheel controlling a front, hydraulic steering control valve controls the front tilting cylinder to facilitates steering with minimal physical exertion.

Abstract: A highly stable concrete saw for cutting crack control relief grooves features a stabilized and reinforced carriage. The carriage frame comprises a generally C-shaped, rigid metal weldment having a closed side extending between a closed front and closed rear. The opposite side is partially open at the bottom, but closed at the top by an elevated reinforcing bridge that connects the front and rear of the frame. The frame substantially surrounds and pivotally captivates a rigid subframe supporting the drive motor and the blade assembly. The carriage comprises a pair of rigid, inwardly offset and downwardly projecting tabs at its front and rear. The tabs are line bored to journal elongated axles that mount front and rear pairs of resilient rollers. Angled scraper assemblies projecting downwardly in front of each pair of rollers deflect away loose debris to maintain a smooth travel path for the carriage.

Abstract: A motorized finishing machine has a rotatable guard system enabling it to finish concrete surfaces next to walls, posts, conduits, or other obstacles. Deployed as a concrete trowel, the machine comprises an internal combustion motor that powers a gearbox to revolve a downwardly projecting rotor. Numerous radially spaced-apart finishing blades controlled by the rotor frictionally contact the concrete surface being treated. A protective guard, which circumscribes the rotor, is rotatably suspended by a plurality of rollers. The guard, which is shaped somewhat like a truncated cone, comprises an inner ring coaxially secured above a larger diameter, outer ring. Radially spaced apart spokes extend between the upper and lower rings and brace the guard. The bearing-equipped rollers mounted by radially, spaced-apart arms have upper and lower flanges. The inner guard ring is captivated between the rollers, and it is vertically constrained between the roller flanges.

Abstract: A powered riding trowel comprises a pair of releasable, protective, quick access hoods that may be unlatched to quickly expose the power means for service without structural disassembly. In a preferred embodiment, the twin hoods are hinged to the frame. The trowel seat is mounted on an upper planar surface of a releasable shroud disposed between the hoods. The shroud front and rear are preferably removably latched to the frame. Major portions of the shroud and the hoods are formed from rigid, supportive material having airflow pathways for cooling and ventilating the normally protected trowel interior. In an alternative embodiment both hoods are releasably coupled to the frame by spring biased latches.

Abstract: A powered concrete finishing trowel comprises a variable ratio drive train to power one or more revolving rotors. One or more internal combustion motors power two or more downwardly projecting rotors comprising blades that frictionally contact the concrete surface. The rotors are shaft driven by reduction gear boxes. By tilting the rotors steering forces are developed. A variable gear drive unit comprises a variable ratio pulley driven by the motor. A second pulley drives the gear box input shaft, with a drive belt entrained between the pulleys. A linear actuator projecting outwardly from a stationary mounting plate terminates at a bracket assembly whose opposite end is pivoted to a rigid stabilizer that structurally compliments the linear actuator, establishing a fulcrum action applied to the bracket center. The linear actuator deflects the bracket assembly to axially displace portions of the variable ratio pulley to change the effective pulley diameter.

Abstract: A powered riding trowel comprises a protective, quick access support shroud that may be unlatched to quickly expose the power means for service without structural disassembly. The trowel seat is mounted on top of the upper planar surface of the shroud. The shroud front and rear are preferably formed from rigid, supportive material having airflow pathways for cooling and ventilating the shroud interior. Opposite shroud ends integral with the top surface angularly depend outwardly and downwardly. In the best mode one shroud end is hinged to the trowel frame, and the opposite end is releasably coupled to the frame by spring biased latches. The preferred hinge structure comprises an outer hinge portion formed by a pivotal connection of the bottom of one shroud end. A cooperating inner hinge defined by at least one pair of inner braces is coupled to a pneumatic dampener that pivotally terminates within the shroud interior.

Abstract: A high performance, multiple rotor riding trowel for finishing concrete and hydraulic controls therefor, enabling complete hand control to the operator of steering, propulsion, and blade pitch. A rigid trowel frame mounts two or more downwardly-projecting, bladed rotor assemblies that frictionally engage the concrete surface. The rotor assemblies are tilted with double acting hydraulic cylinders to effectuate steering and control. Double acting hydraulic cylinders also control blade pitch. A joystick system enables the operator to hand control the trowel with minimal physical exertion. The joystick system activates solenoid control valves that in turn energize the various hydraulic cylinders that tilt the rotors and alter blade pitch. The rotor gearboxes are mounted to tiltable, pivot steering boxes secured to the frame within suitable mounting regions bounded by rigid frame elements. The rotor assembly blades contact plastic concrete to finish the surface while supporting the trowel.

Abstract: A high power, contra-rotating, twin engine riding trowel for finishing concrete comprises twin, downwardly projecting rotors that counter-rotate simultaneously. An operator sits in a seat mounted to the frame and steers the rotors with a pair of primary control levers that tilt the rotors to generate steering forces. The engines counter-rotate while establishing generally coaxial, horizontal axes of rotation. Each engine drives a rotor through a driveshaft. Both driveshafts establish generally coaxial axes of rotation that are generally parallel to the axes of rotation of the engines. Each driveshaft extends to a gearbox to transfer power to the rotor. The gearboxes are interchangeable and mounted to tiltable, pivotable steering boxes secured to the frame. A first reversing linkage couples the lever means to the arm means. A second reversing linkage means is suitably coupled to one rotor gearbox to reverse tilt it for steering.

Abstract: A triple roller tube concrete finisher that uses rotating tubes to strike-off, screed and finish concrete. The machine rides upon concrete forms and comprises a box-like, generally parallelepiped, frame supported by a plurality of rotary rollers. The frame houses an engine, cleaning system and a hydraulic system. The engine powers the hydraulic system that rotates the rollers. Two of the rollers provide locomotion to the machine while simultaneously screeding and finishing concrete the machine moves over. Preferably, these drive rollers are bidirectional to facilitate forward and rearward movement of the finishing machine. One of the rollers functions like a strike-off to prevent ride up. This roller rotates counter to the drive rollers to grade and displace excess unlevel concrete away from the leading edge of the machine. Preferably, the vertical height of the strike-off roller and its axis of rotation may be adjusted to vary the resulting depth of the concrete passing thereunder.

Abstract: A concrete finishing tool that quickly changes in length to selectively bypass columns, curbs and other obstacles during concrete finishing includes a unique foldable bypass system at an extremity that can be folded between extended and retracted positions. When actively deployed the bypass is aligned for finishing concrete. In the retracted position it assumes a clearance orientation out of contact with the concrete. The bypass comprises a finishing wing for contacting concrete, a linkage system and a vibrator. The wing may comprise a forward strike-off and a trailing float. The linkage system comprises a pair of abutting links interconnected at an axially offset intermediate pivot point. One of the links is pivotally attached to the tool and the other link is pivotally attached to the wing. When the linkage system folds the links are moved between length additive and length subtractive orientations.

Abstract: An automatic, self locking clutch system effectuates blade pitch control on concrete finishing trowels. The clutch instantly releases upon the touch of the operator. A trowel has a downwardly projecting, motor-driven rotor comprising a plurality of radially spaced apart finishing blades directly contacting the concrete surface. A handle extends from a rigid frame and terminates in handlebars grasped by an operator. Control arms extend from the blades into contact with a plate to vary pitch by conventionally rotating the blades about their longitudinal axis. A clutch operatively interconnects a lever and a linkage extending to the swash plate. The clutch comprises a tubular housing coaxially receiving a drive shaft that rotatably controls an internal rotor. A set of spring biased, cylindrical rollers are confined within channels defined in the rotor between major and minor lobes thereof.

Abstract: A self-propelled paver that distributes, consolidates, places and finishes polymer concrete to rapidly resurface roadbeds. A mobile, wheeled chassis mounts an adjustable hopper that receives premixed polymer from a mixer truck that precedes the paver. A finishing assembly secured to the chassis has a distribution assembly for applying concrete transversely across the surface, and a trailing finishing screed that surfaces and densifies the concrete. An active, hydraulic suspension dynamically orients the chassis and the finishing assembly with the roadbed. Individual height adjusting cylinders can be extended or contracted by an automatic grade control that logically senses grade through an external string line. The distribution system comprises an open bottom exposing the surface to be paved, and an open top adapted to receive concrete from a trough extending from the hopper. A bidirectional auger is rotatably disposed within a distribution box for moving concrete upon the surface.

Abstract: A torsionally stabilized automatic grade control system for finishing plastic concrete is capable of controlling a variety of different elongated, multi-section concrete finishing tools such as a vibratory screed or the like, with or without forms. Skis that support the device facilitate sliding, winch driven movement over and through plastic concrete. Spaced apart, vertically upwardly extending towers support the device; they are disposed periodically along the length of the finishing tool. Each tower comprises a pair of extensible, spaced apart stanchions hinged to the skis and disposed on opposite sides of the tool. An upper strut extends between the stanchions. A sleeve coaxially fitted to each stanchion is synchronized with the opposite sleeve by a rigid transverse bridge. The bridge is adjustably coupled to the strut. The upper portion of the stanchions comprises a hydraulic cylinder. Each cylinder is controlled by an adjacent sensor secured to the strut to maintain the attached tool level.

Abstract: An automatic grading control device for finishing plastic concrete controls several different elongated, multi-section concrete finishing tools such as vibratory screeds or the like, with or without forms. Supporting skis facilitate sliding, winch driven movement of the device relative to the plastic concrete. Spaced apart and vertically upwardly extending towers are supported by the skis and disposed periodically along the length of the finishing tool. Each tower comprises a pair of elongated, spaced apart stanchions disposed on opposite sides of the tool that are braced with a rigid, adjustable upper strut. The strut extends between the stanchions and forms the top of the tower. Movable sleeves coaxially fitted to the stanchions are synchronized by rigid transverse bridges that extend between the sleeves above the tool. Hydraulic or pneumatic cylinders extending between the strut and the bridge raise and lower the tool thereby controlling level.