Abstract: A roller tube concrete finishing machine includes retractable vibration gangs that can be selectively immersed within wet concrete and then retracted with parallelogram linkage. Spaced-apart, drive parallel rollers are journaled between frame ends for supporting and propelling the machine upon and between parallel form rails. A front roller provide a strike-off function. The vibration gangs are deployed by a retractable, parallelogram linkage that moves them forwardly and downwardly for operation, or which retracts the vibrators inwardly and upwardly relative to the frame. When the vibrators are retracted, the are withdrawn upwardly from the concrete and retracted rearwardly towards the machine front to reduce machine dimensions. Substantial retraction of the vibrators prevents subsequent interference with the rebar below. Vibrator retraction reduces overall machine dimensions for clearance and shipping purposes, with gang vibration arrays nested upwardly and inwardly proximate the front of the machine.

Abstract: A roller tube concrete finishing machine includes retractable vibration gangs that can be selectively immersed within wet concrete and then retracted with parallelogram linkage. Spaced-apart, drive parallel rollers are journaled between frame ends for supporting and propelling the machine upon and between parallel form rails. A front roller provide a strike-off function. The vibration gangs are deployed by a retractable, parallelogram linkage that moves them forwardly and downwardly for operation, or which retracts the vibrators inwardly and upwardly relative to the frame. When the vibrators are retracted, the are withdrawn upwardly from the concrete and retracted rearwardly towards the machine front to reduce machine dimensions. Substantial retraction of the vibrators prevents subsequent interference with the rebar below. Vibrator retraction reduces overall machine dimensions for clearance and shipping purposes, with gang vibration arrays nested upwardly and inwardly proximate the front of the machine.

Abstract: High performance, multiple rotor, hydraulically driven riding trowels for finishing concrete have unloader valve circuitry for controlling hydraulic pressure. Each trowel has a rigid frame with two or more downwardly-projecting, bladed rotor assemblies that finish concrete. The rotor assemblies are tilted manually or hydraulically to effectuate steering and control. Blade pitch is controlled manually or hydraulically. The unloader valve system monitors drive pump pressure with a shuttle valve to derive an unloader pilot signal. A sequence valve responds to the unloader pilot signal to control a pressure valve that bypasses the normal foot control valve in an overpressure situation. The pressure control head signal normally applied to the hydraulic drive motor control heads is modified with a feedback signal to automatically control the associated pump swash plates. A gearbox may be disposed between the drive motors and rotors. Piston type and gear and vane type motors may power the rotors.

Abstract: High performance, multiple rotor, hydraulically driven riding trowels for finishing concrete have unloader valve circuitry for controlling hydraulic pressure. Each trowel has a rigid frame with two or more downwardly-projecting, bladed rotor assemblies that finish concrete. The rotor assemblies are tilted manually or hydraulically to effectuate steering and control. Blade pitch is controlled manually or hydraulically. The unloader valve system monitors drive pump pressure with a shuttle valve to derive an unloader pilot signal. A sequence valve responds to the unloader pilot signal to control a pressure valve that bypasses the normal foot control valve in an overpressure situation. The pressure control head signal normally applied to the hydraulic drive motor control heads is modified with a feedback signal to automatically control the associated pump swash plates. A gearbox may be disposed between the drive motors and rotors. Piston type and gear and vane type motors may power the rotors.

Abstract: A high performance, multiple rotor, hydraulically driven riding trowel for finishing concrete includes a rigid trowel frame with 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. Hydraulic pressure to the rotors is monitored and controlled by an unloader valve system that monitors drive pump pressure with a shuttle valve to derive an unloader pilot signal. A sequence valve responds to the unloader pilot signal to control a pressure valve that bypasses the normal foot control valve in an overpressure situation. The pressure control head signal normally applied to the hydraulic drive motor control heads is modified with a feedback signal to automatically control the associated pump swash plates.

Abstract: A high performance, multiple rotor, hydraulically driven riding trowel for finishing concrete includes a rigid trowel frame with 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. Hydraulic pressure to the rotors is monitored and controlled by an unloader valve system that monitors drive pump pressure with a shuttle valve to derive an unloader pilot signal. A sequence valve responds to the unloader pilot signal to control a pressure valve that bypasses the normal foot control valve in an overpressure situation. The pressure control head signal normally applied to the hydraulic drive motor control heads is modified with a feedback signal to automatically control the associated pump swash plates.

Abstract: Methods and apparatus for screeding freshly placed concrete in which the acoustic impedance of the treating equipment is made substantially equal to the acoustic impedance of the concrete slab. Portions of the screed contacting the plastic concrete are matched to an acoustic impedance approximating the acoustic impedance of plastic concrete, promoting the energy transferred to the concrete. The acoustic matching material is fabricated from a material that has an acoustic impedance within 67% to 150% of the acoustic impedance of the concrete being finished. The acoustic matching material has an abrasion resistance of no greater than 150 measured using ASTM Method G-65 where steel is given a rating of 100. The preferred matching material comprises ultra-high molecular weight polyethylene (UHMWPE) plastic.

Abstract: Pans 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 plastic 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 plastic 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: 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: 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: 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: A high performance, riding trowel for finishing concrete comprises damage-preventing edge guard systems that accommodate destructive forces occasioned by collisions or impacts. Downwardly projecting, motor-driven rotor assemblies gimbaled to the frame contact the concrete with multiple blades for finishing. The rotors are tilted with linkages ideally controlled by a powered system that enhances operator control. A two-piece guard system is concentrically disposed over and rotatably associated with each rotor. The guard system comprises a captivating guard frame borne by the rotor and tilted during steering, which captivates and supports a rotatable ring guard portion that may non-destructively impact obstacles. The guard system frame suspends a plurality of rollers comprising upper and lower flanges. The rotatable guard ring is captivated upon the rollers, being vertically constrained between the flanges.

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 a joystick operated electro-hydraulic control circuit enabling complete joystick control to the operator. The rigid trowel frame mounts two spaced-apart, downwardly projecting, and bladed rotors that frictionally contact the concrete surface. The rotors 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 proportional joystick system directly controls electrical circuitry that outputs proportional control signals to electrically controlled, proportional, pressure-reducing valves in line with the tilting cylinders. The hydraulic circuitry comprises a motor driven pump delivering pressure to a flow divider circuit. A bypass-valve in line before the flow divider enables an operator to customize the trowel steering characteristics.

Abstract: A two-person floating screed with laser-operated, automatic grade control apparatus for finishing plastic concrete is transformable for different operations. A rigid, transversely oriented float mounts a strikeoff for initially contacting and leveling rough, freshly poured concrete. In one form of the invention the screed merely floats upon the concrete surface. In an alternative embodiment, lightweight ski assemblies support the screed over the subgrade. The skis secure upwardly projecting screw jacks that removably couple to the screed and control elevation of the transverse float in response to laser signals. Each worker has a separate handle mechanism pivotally associated with the float. Separate, light-weight power sources are carried by each worker in a suitable backpack to power the screw jacks. Laser sensors mounted on vibration dampened stanchions emanating from the float respond to external laser beacons and display grade information so that the workers can make manual adjustments.

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 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.