Patent Application
20070163565
1. Field
These inventions relate to concrete saws.
2. Related Art
In the concrete industry, large slabs of concrete are used to form road to beds, building floors and other structures used for its strength and durability. Seams, grooves or other cuts in the concrete may be made in the slabs to form expansion joints, control stress cracks as the slabs cure or to form channels or openings in the slabs to accept other structures. Concrete saws are used to cut the seams, grooves or other openings, and such concrete saws are often very heavy and difficult to move along the concrete slab. For large or heavy construction applications, heavy self-propelled saws or other large concrete saws are used. Examples of concrete saws and their construction and operation can be found in a number of patents, including U.S. Pat. No. 5,809,985, entitled “Self-Propelled Saw,” U.S. Pat. No. 5,743,247, entitled “Method and Apparatus for Safe Operation of Self-Propelled Concrete Saw,” U.S. Pat. No. 5,680,854, entitled “Self-Propelled Saw,” U.S. Pat. No. 5,477,844, entitled “Slurry Recovery System for a Wet Cutting Saw,” and U.S. Pat. No. 4,664,645 entitled “Blade Drive Shaft Assembly,” all of which are incorporated herein by reference. During setup and operation of the saw, an operator walks behind the saw to control the direction, cutting speed, cutting depth and other operating conditions under which the saw operates. The saw includes one or more wheels allowing the saw to move along the concrete and a frame supported by the wheels on which is mounted a motor or other power supply for operating a saw blade and often for driving one or more wheels to move the saw along the concrete surface. One or more handles extend behind the saw about the level of an operator's hands to allow the operator to manually position the saw. Typically, the saw blade is in the front of the saw and handles extend behind the saw.
For a typical straight cut, the operator aligns the saw blade and often a cutting guide with the intended cutting path. The saw is maneuvered with the saw blade raised above the concrete until the blade and cutting guide are aligned with the cutting path. As the saw blade engages the concrete or other surface to be cut, the blade cuts into the concrete to the desired depth, such as the depth selected by the operator. At the desired depth, the drive wheels are engaged to propel the saw forward to cut the desired slot or groove, which typically follows a straight cut path.
For some saws, such as the self-propelled saws, a number of different sizes of blades can be used on the saw. However, because different sizes of blades have optimum operating conditions, such as optimum blade speeds, it is desirable to operate one blade under one operating configuration, such as at one speed, and a different sized blade under another operating configuration, such as at another speed. Different operating configurations can be carried out by running the saw motor at different speeds, changing the motor output and blade input pulleys to produce different ratios, or in other ways. Saws having gearboxes that can operate at multiple speeds can make easier to change the operating configuration when changing from one blade size to another.
A concrete saw that can operate at multiple speeds may have a gearbox for operating the saw at more than one speed. The gearbox can be configured to have a relatively small volume. The gearbox can also be configured to make changing from one speed to another than saws without multiple speed gearboxes. The gearbox may also be configured in a self-propelled saw to allow the saw to be moved from one location to another without engaging the saw blade drive shaft. Additionally, the gearbox may be configured so as to be relatively insulated from loading and stresses experienced by a saw blade during cutting.
In one example of a concrete saw, a motor is provided for driving a blade support element. A drive element, for example a gear, is configured to be driven by the motor and provides driving input to drive the blade support element. The drive element is also configured so that it is part of a mechanism by which the mechanism has a neutral position. In the neutral position, the drive element does not drive the blade support element. In one configuration, the drive element changes to a neutral configuration by disengaging from an output element and in another configuration an input element disengages from the drive element. In another configuration, the drive element, for example in the form of a gear, can move from an engagement position about a splined shaft to a disengaged position about the shaft, for example past a point on the shaft where the splines terminate. A neutral position allows the motor to be on, or the saw moved with the motor on, but without the blade turning. The blade is disengaged from the motor.
In another example a concrete saw, a motor is provided for driving a blade support element. A drive element, for example a plurality of gears between the motor and the blade support element drive the blade at at least two different speeds. In one example, the gears are configured to include a neutral position. In one configuration, the saw can operate at three speeds. In another configuration, flexible drive elements such as belts can be used to couple or transfer drive from the gears to the blade support element. The gears can be arranged on as few as two shafts, permitting a relatively small gearbox. The gearbox can be driven directly from the motor, for example through bevel gears, and the motor can be arranged perpendicular to the blade support element, such as a blade drive shaft.
In another example, a concrete saw having a motor for driving a cutting blade includes a gearbox for driving the blade at at least two different speeds where the gearbox has no more than two shafts supporting the gears. The gearbox can be configured to operate at three different speeds, and can include at least one and preferably two neutral positions. In a saw with three speeds, the gears sets can be arranged efficiently by having the shift sequence out of numerical order, for example from high, to low, to medium.
In a further example of a concrete saw, the motor drives a saw blade output drive shaft through a gearbox having an output for driving a drive belt between the gearbox and the blade drive shaft. The gearbox can be driven by a gear coupled to a motor output shaft for engaging and driving a gear in the gearbox. The motor output shaft can be inline with the direction of saw travel. In one configuration, the gearbox can operate at at least two speeds, or three speeds. The gearbox may also have one or two neutral positions.
These and other examples are set forth more fully below in conjunction with drawings, a brief description of which follows.
This specification taken in conjunction with the drawings sets forth examples of apparatus and methods incorporating one or more aspects of the present inventions in such a manner that any person skilled in the art can make and use the inventions. The examples provide the best modes contemplated for carrying out the inventions, although it should be understood that various modifications can be accomplished within the parameters of the present inventions.
An example of a saw and of a method of making and using the saw are described. Depending on what feature or features are incorporated in a given structure or a given method, benefits can be achieved in the structure or the method. For example, saws using belt drives between a multi-speed gear box and a blade drive shaft may result in the gearbox having a longer lifetime. Additionally, some saw configurations may also benefit from the use of smaller components.
These and other benefits will become more apparent with consideration of the description of the examples herein. However, it should be understood that not all of the benefits or features discussed with respect to a particular example must be incorporated into a saw, component or method in order to achieve one or more benefits contemplated by these examples. Additionally, it should be understood that features of the examples can be incorporated into a saw, component or method to achieve some measure of a given benefit even though the benefit may not be optimal compared to other possible configurations. For example, one or more benefits may not be optimized for a given configuration in order to achieve cost reductions, efficiencies or for other reasons known to the person settling on a particular product configuration or method.
An example of a saw configuration and a method of making and using the saw are described herein, and some features have particular benefits in being used together. However, even though these apparatus and methods are considered together at this point, there is no requirement that they be combined, used together, or that one component or method be used with any other component or method, or combination. Additionally, it will be understood that a given component or method could be combined with other structures or methods not expressly discussed herein while still achieving desirable results.
In one example of a saw (
In the example shown in the drawings, the gearbox 46 is rigidly mounted to and supported on the engine by the cover plate 48. The cover plate 48 is bolted to a front of the engine, and the input shaft 44 to the gearbox engages the splined output element 42 in the engine. The splined output element may be a drive assembly which may, but need not, include a clutch or other means for disengaging the motor from the gearbox. One example of a suitable clutch arrangement is shown in FIG. 9 of U.S. Pat. No. 5,810,448. In other configurations for the gearbox, the gearbox can be separate from the cover plate and/or coupled to the engine output through other means. In the present example, the engine 38 is aligned and has its output shaft with the output element 42 aligned with the direction of travel of the saw. Therefore, the output shaft and output element 42 are directed parallel to the direction of travel, and perpendicular to the transverse orientation of the blade drive shaft 40. This engine orientation allows a larger engine to be placed on the saw within the same overall saw envelope compared to a saw having an engine oriented transverse to the direction of travel. Additionally, this orientation permits direct coupling of the gearbox 46 to the engine output at the front of the saw, so that the added volume occupied by the gearbox does not increase the width of the saw.
The gearbox 46 is mounted directly to the engine block, which in turn is supported on the frame through isolator elements (not shown). As a result, engine vibration and gearbox vibration that may occur during operation can be isolated or insulated from the frame, and therefore from the handles 70 at the rear of the saw (
The gearbox in the example shown in the drawings includes a plurality of gear sets on a plurality of gear shafts (described more fully below) that can be used for driving the saw blade at different speeds for a given input rpm from the engine. The saw includes a speed selector 72 on the gearbox 46. In the example shown in drawings, the speed selector includes a handle 74 captured in a shift pattern 76, which is mounted to the engine. The shift pattern guides the operator in selecting the appropriate position for the handle 74 for the desired speed setting or neutral position. The shift pattern may also include appropriate indicators for the speed and neutral positions, such as “M” for medium speed, “N” for neutral, “L” for low, and “H” for high (as shown in
The handle 74 is pivotally coupled to a transverse shift bar 78, which in turn is coupled through connector bars 80 to a gear selector shaft 82 extending through appropriate seals and bearings into the gearbox. The transverse shift bar 78 and the connector bars 80 transfer the handle movement to the gear selector shaft 82.
Considering the present example of the gearbox in more detail with respect to
Specifically, the gearbox 46 includes an externally splined output shaft 94 supported by a pair of radial bearings 96 in the gearbox housing. The splined shaft includes output shaft ends 98 and 100 for engaging and supporting the output shaft pulleys 50 and 52, respectively, shown in
The output shaft 94 also includes at least one driven or output gear for engaging the drive gear, and at least one or the other of the drive gear and the output gear have a configuration by which the gears disengage or otherwise have a neutral configuration, thereby disengaging the blade drive shaft from the motor. In the neutral position, the gear does not drive the blade support element. In one possible configuration, the drive gear changes to a neutral configuration by disengaging from the output gear, and in another configuration the output gear changes to a neutral configuration by disengaging from the input element. Other configurations are possible as well, including one where the gear can move from an engagement position about a splined shaft to a disengaged position about the shaft, for example past a point on the shaft where the splines terminate. The neutral position allows the motor to be on, or the saw moved with the motor on, but without the blade turning. The blade is disengaged from the motor.
In the example shown in the drawings, the output shaft 94 includes driven or output gears corresponding to the driving gears on the drive shaft 90, as described more fully below. The driven gears engage the splined shaft 94 and are axially fixed to a collar 102 and fixed relative to one another, so that movement of the collar 102 also moves axially the gears on the splined shaft 94 in unison. The collar 102 rotatably engages a gear selector fork 104 in such a way that the collar moves axially along the splined shaft when the gear selector fork moves axially. The collar 102 rotates with the splined shaft within a selector fork, which remains substantially rotationally fixed while the splined shaft rotates. The gears on the drive shaft and the output shaft are sized and arranged on their respective shafts in such a way that they have engaged positions and neutral positions.
The gear selector fork 104 is fixed to and supported on the gear selector shaft 82, and moves axially with the gear selector shaft. The gear selector shaft includes appropriate bearings 106 and seals 108 to reliably support the selector shaft in the gearbox housing. The handle 74 (
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While other gear configurations and combinations are possible, the configurations and combinations shown in the drawings provide to neutral positions, permitting easier shifting into and out of engagement, as well as allowing the operator to move the saw without the blade turning. The gearbox also conveniently has only two shafts also permitting a relatively small gearbox. The configurations also permit a relatively small sized gearbox. Additional blade speed ratios can be achieved by changing output or blade drive shaft pulleys.
Having thus described several exemplary implementations, it will be apparent that various alterations and modifications can be made without departing from the concepts discussed herein. Such alterations and modifications, though not expressly described above, are nonetheless intended and implied to be within the spirit and scope of the inventions. Accordingly, the foregoing description is intended to be illustrative only.
