Patent Application
20120163912
1. Field of the Invention
The invention relates generally to concrete finishing trowels and, more particularly, to a transport system for a powered finishing trowel. The invention additionally relates to a concrete finishing trowel, such as a riding trowel, having an integrated transport system that enables wheeled transport of the trowel within a worksite and to and from a worksite.
2. Description of the Related Art
A variety of machines are available for smoothing or otherwise finishing wet concrete. These machines range from simple hand trowels, to walk-behind trowels, to self-propelled riding trowels. Regardless of the mode of operation of such trowels, the powered trowels generally include one to three rotor assemblies that rotate relative to the concrete surface.
Riding concrete finishing trowels can finish large sections of concrete more rapidly and efficiently than manually pushed or guided hand-held or walk behind finishing trowels. Riding concrete finishing trowels typically include a frame having a cage that typically encloses two, and sometimes three or more, rotor assemblies. Each rotor assembly includes a driven shaft and a plurality of trowel blades mounted on and extending radially outwardly from the bottom end of the driven shaft. The driven shafts of the rotor assemblies are driven by one or more engines mounted on the frame and typically linked to the driven shafts by gearboxes of the respective rotor assemblies.
The weight of the finishing trowel, including the operator, is transmitted frictionally to the concrete surface by the rotating blades, thereby smoothing the concrete surface. The pitch of individual blades can be altered relative to the driven shafts via operation of a lever and/or linkage system during use of the machine. Such a construction allows the operator to adjust blade pitch during operation of the power trowel. As is commonly understood, blade pitch adjustment alters the pressure applied to the surface being finished by the machine. This blade pitch adjustment permits the finishing characteristics of the machine to be adjusted. For instance, in an ideal finishing operation, the operator first performs an initial “floating” operation in which the blades are operated at low speeds (on the order of about 30 rpm) but at high torque. Then, the concrete is allowed to cure for another 15 minutes to one-half hour, and the machine is operated at progressively increasing speeds and progressively increasing blade pitches up to the performance of a finishing or “burning” operation at the highest possible speed—preferably above about 150 rpm and up to about 200 rpm.
During use, the riding trowel is supported by the engagement between the blades and the underlying concrete material. The blades may rest directly on the concrete or on pans. To some extent, the weight of the machine assists the finishing process.
Although the weight of the machine can be beneficial for providing efficient, robust, and powerful trowel operation, the weight of the machine is also detrimental to non-use transportation of the trowel, i.e. while moving the trowel within the worksite or to or from a worksite without operating the blades. Commonly, supplemental equipment, such as a skid loader, a backhoe, or the like, is utilized to move the machine to and from a work surface. Some concrete finishing trowels are fitted with lift points for attachment to a chain for this purpose. These machines experience difficulty in moving the trowel in certain work environments. For instance, for large slab on grade jobs where a number of pours are required to complete a floor, the green concrete is unable to support the heavy machinery for several weeks after a pour. Forklifts and similar devices therefore cannot access the trowels for transport.
Further, forklifts and other prior art transport systems used in lieu of on-board wheel transports are typically constructed to support weights of approximately between 1600-2300 pounds; however, concrete finishing trowels may weigh in excess of 2300 pounds. For instance, some known trowels may weigh as much as 2800 pounds, making the prior art transport systems unsuitable for use therewith. Alternatively, when no such equipment is available or the trowel must be used in a location which is not accessible by or otherwise cannot accommodate such equipment, two or more laborers are required to manually lift and move the machine. This is a labor intensive and physically demanding technique for moving such machines.
Previous trowel transport systems have been disclosed which include a number of wheels or casters that are securable to the frame of the trowel. These transport systems typically take the form of “wheel kits” that are sold as aftermarket accessories. The wheel kits comprise a number of wheel assemblies that are irremovably attached to the trowel. One such removable wheel kit or “dolly” is disclosed in U.S. Pat. No. 5,238,323 to Allen et al. The wheel kit disclosed in the Allen '323 patent includes a pair of wheel assemblies secured to generally opposite sides of the exterior of the cage of a riding trowel. A separate jack is provided for each wheel assembly so that each jack independently raises and lowers a separate wheel assembly relative to the frame. When lowered, the wheels support the trowel such that a single user can move the entire trowel by simply pushing or pulling it in an intended direction.
Although such systems enhance the mobility of power trowels, they are not without their drawbacks.
For instance, because the wheel assemblies of the Allen '323 patent are located outboard of the cage, they increase the overall footprint of the machine. Increasing the footprint of the machine increases the space occupied by the machine. Accordingly, it may prevent the machine from being transported in the beds of some trucks without removing the wheel assemblies. Increasing the footprint of the machine also detracts from a user's ability to position the machine close to the perimeter of an area to be worked (commonly referred to as a “pour area”) or an obstacle in or adjacent to a pour area. This limitation is problematic because users of finishing machines prefer that the machine finish as much of the pour area as possible. The areas that cannot be finished due to the interference between the wheel assemblies and the obstructions must be finished by hand, increasing the amount of hand work associated with a given pour. This problem can be avoided only by removing the wheel assemblies prior to commencing a finishing operation.
Transport systems such as the one disclosed in U.S. Pat. No. 5,238,323 are also relatively inefficient. To raise the machine, the operator must manually operate two separate jacks on opposite sides of the machine. In addition, unless care is taken to operate both jacks the same amount, one side of the machine may be higher than the other during transport, reducing the stability and maneuverability of the machine. Moreover, the wheel kit of the '323 patent is not integrated into the trowel but, rather, is coupled to the machine as an accessory that typically is installed and removed at the worksite. Like any accessory, these wheel kits are susceptible to being lost, left behind, or damaged at job sites because they are set aside when not in use.
U.S. Pat. No. 7,771,139 to Grahl discloses a transport system in which two or more spaced wheels are concurrently movable by manual manipulation of a single lifting jack to adjust the position of the wheels relative to the blades of the finishing machine. The wheel assemblies of the '139 patent also are located inside the “footprint” of the machine, permitting the machine to be operated with the wheel assemblies installed without interference from obstructions in or adjacent the pour area. They also are integrated into the remainder of the machine. While the device of the '139 patent is thus an improvement over the '323 patent, the presence of even a single jack may prove to be cumbersome during maintenance of the trowel. Manually operating a jack also is labor intensive. The need to manually actuate the jack or other lifting mechanisms of traditional wheel kits is especially problematic with large, hydraulically powered trowels. These trowels typically have an internal combustion engine coupled to the rotor assemblies by a hydrostatic drive system including a pump and multiple hydraulic motors, one of which is provided for each rotor assembly. The trowels are steered by tilting the rotor assemblies using hydraulic cylinders. Each rotor assembly may have a diameter of 5 feet, rendering the trowel over 10 feet long. The combined weight of the trowel and the operator may exceed 2,500 lbs—triple that of traditional manually steered powered trowels having a mechanical gearbox coupling each rotor assembly to the internal combustion engine. This dramatic difference in weight renders traditional manually actuated jacks and their associated wheel kit components ill-suited for use with hydraulically powered trowels.
Accordingly, there is also a need for a wheeled transport system for a concrete finishing trowel that requires less effort to deploy than previously-known transport systems.
There is also a need for a trowel transport system which is integrated into the trowel and which, therefore, need not be attached to the trowel by the operators and is not at risk of damaged when removed from the trowel or of being lost.
There is also a need for an easily-deployed concrete finishing trowel transport system that does not increase the footprint of the machine. A transport system that is integrated into a powered trowel and that eliminates the need for an external lifting mechanism such as a jack is also desired.
It is further desired to provide a trowel transport system that can be implemented into a number of machine configurations as well as one that is relatively simple to operate, inexpensive to produce, and simple to maintain.
The present invention provides a power concrete finishing trowel transport system that meets one or more of the above-identified needs. A transport system according to one aspect of the invention includes at least two of spaced wheel assemblies that are movable by actuation of one or more powered actuators to move the wheel assemblies from a raised or stowed position in which the wheels are disposed above a trowel support surface to a lowered or deployed position in which the wheels support the trowel on the support surface. Each wheel assembly may include two or more spaced wheels. In this case, a single powered actuator such as a hydraulic cylinder may be operable to deploy the wheels of each assembly. The powered actuators may be controlled concurrently by a single switch.
Another aspect of the invention is to provide a power concrete finishing trowel that meets the first principal aspect and that is simple to operate, does not substantially increase the weight of the finishing machine, and is inexpensive.
Yet another aspect of the invention is to provide a power concrete finishing trowel with a transport system that meets one or more of the first and second aspects and that does not otherwise increase the footprint of the finishing machine.
Still another aspect of the invention is to provide a power concrete finishing trowel transport system that is integrally formed with the concrete finishing trowel. In a particularly preferred configuration, the transport system includes two wheel assemblies disposed at the front and rear of the machine, respectively. Each wheel assembly includes a pair of wheels mounted on respective pivoting bracket assemblies, each of which is pivoted on a mount welded to or otherwise rigidly connected to a fork lift tube extending widthwise across the frame. Each set of wheels is raised and lowered by a single double acting hydraulic cylinder having a barrel connected to one of the bracket assemblies and a rod connected to the other bracket assembly. The raising and lowering of the sets of wheels is controlled by the operator via a switch interconnected with both hydraulic cylinders.
A method for satisfying one or more of the above aspects includes providing a power trowel having a frame and at least one rotor assembly that includes a rotatable shaft and a plurality of blades. The method includes actuating one or more powered actuators to move wheel assemblies from a raised or stowed position in which the wheels are above a trowel support surface to a lowered or deployed position in which the wheels support the trowel on the support surface. Two or more sets of wheels may be provided at opposite sides of the machine. In this case, the actuating step my include manipulating a single actuator such as a hydraulic cylinder to deploy the wheels of each set. The powered actuators may be controlled concurrently by a single switch.
These and other aspects, advantages, and features of the invention will become apparent to those skilled in the art from the detailed description and the accompanying drawings. It should be understood, however, that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof. It is hereby disclosed that the invention include all such modifications.
Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which:
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The rotor assemblies 32 and 34 rotate towards the operator, or counterclockwise and clockwise, respectively, to perform a finishing operation. Cage 24 is positioned at the outer perimeter of trowel 20 and extends downwardly from frame 26 to the vicinity of the surface to be finished. Cage 24 generally defines a footprint of trowel 20. The pedestal 30 is positioned generally longitudinally centrally on deck 28 at a rear portion thereof and supports operator's seat 36. A fuel tank 38 is disposed adjacent the left side of pedestal 30, and a water retardant tank 40 is disposed on the right side of pedestal 30. A lift cage assembly 42, best seen in
Each rotor assembly 32, 34 includes a plurality of circumferentially-spaced blades 44 supported on a driven shaft (not shown) via radial support arms 46 and extending radially outwardly from the bottom end of the driven shaft so as to rest on the concrete surface. Both rotor assemblies 32 and 34, as well as other powered components of the finishing trowel 20, are driven by a hydrostatic drive system located under the frame. The hydrostatic drive system includes a hydrostatic pump that is powered by an internal combustion engine 61 to circulate hydraulic fluid to a pair of hydraulic drive motors, each of which drives a respective rotor assembly 32 or 34 to rotate. Operation of the hydrostatic pump is governed by a solenoid controlled electro-hydraulic proportional control valve that controls the output of the pump based on a proportional current signal generated by a foot pedal 43 and transmitted by a controller (not shown).
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The wheeled transport system of this embodiment includes front and rear wheel assemblies 58, 60 located generally centrally of the frame and spaced longitudinally from one another so as to be positioned in front of and behind the operator's seat 36, respectively. They are located just inside the perimeter of the cage 24 in the illustrated embodiment but could be spaced closer to one another, if desired, to accommodate other components of the machine such as frame components, steering system components, or drive system components. In the preferred embodiment, however, they should be spaced far enough apart to prevent or at least inhibit the machine from rocking about the machine's longitudinal centerline. They also should not extend beyond the widest perimeter of the cage and, as such, should not increase the footprint of the trowel 20. It should be noted that, rather than being spaced longitudinally from one another, the wheel assemblies 58 and 60 could instead be located on opposite ends of the machine and spaced from one another laterally rather than longitudinally as in the illustrated embodiment.
The wheel assemblies 58, 60 are raised and lowered by actuation of one or more powered actuator arrangements to move the wheel or wheels of each assembly 58, 60 from a raised, stowed position in which the wheels are above a trowel support surface to a deployed position in which the wheels lift the trowel 20 from the support surface and support the trowel on the support surface. The powered actuators could comprise any powered device or combination of devices, such as linear electric actuators, that are capable of raising and lowering the wheels and the weight of the trowel 20. Hydraulic cylinders 63 currently are preferred. A switch 53 (
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To return the wheels 62 to the lowered, deployed orientation for transport of the trowel 20, the operator actuates switch 53 to retract the cylinder 63. Cylinder retraction pivots bracket 84a clockwise about pin 76a and pivots bracket 84b counterclockwise about pin 76b such that the wheels 62 are lowered into their deployed orientations and again lift the trowel 20 from the ground.
Accordingly, the wheel assemblies 58, 60 are movable via hydraulic cylinders 63 between a non-use, raised, or stowed orientation as shown in
Hence, the inventive system reduces operator effort to configure the riding trowel for non-assisted transportation, provides an efficient means of changing the elevation of the machine and does not adversely affect the footprint of the trowel.
It should be mentioned that elevating trowel 20 with transport system 22 will also be beneficial for purposes other than transport. For instance, after a finishing operation, trowel 20, including the underside of cage 24 and blades 44, must be cleaned to remove residual concrete materials from the machine. Transport system 22 can be deployed to elevate trowel 20 such that a user can quickly clean the underside of the machine. In addition, the wheel assemblies 58, 60 can be deployed to facilitate blade maintenance or replacement or to facilitate the installation of pans on the bottoms of the rotor assemblies.
It is appreciated that a number of alternative arrangements are envisioned with respect to the transport system 22 of trowel 20. For instance, additional wheel assemblies could be provided at other locations on the trowel 20. The wheels of each assembly also could take any number of alternative configurations to that described above. In addition, each double acting cylinder could be replaced by a pair of single acting cylinders, one or more linear electric actuators, or other powered actuators entirely. The switch 53 also could be replaced by one or more switches, levers or other devices capable of controlling operation of one or more actuators.
It is appreciated that many changes and modifications could be made to the invention without departing from the spirit thereof. Some of these changes, such as its applicability to riding concrete finishing trowels having other than two rotor assemblies and even to other self-propelled powered finishing trowels, are discussed above. Other changes will become apparent from the appended claims. It is intended that all such changes and/or modifications be incorporated in the appending claims.
