Patent Application
20170276214
Not applicable
Not applicable
I. Field of the Invention:
This invention relates generally to machine tools for performing in the field milling operations on pipes and shafts and, more particularly, to a gearbox attachable to such machine tools that is readily adaptable so as to permit use of an air motor or a hydraulic motor as a source of power.
II. Discussion of the Prior Art:
Typical of field service machining devices that are conventionally pneumatically or hydraulically driven due to the absence of electrical power at the sites where a machining operation is to be performed, for example, along a pipeline or on shafts that, because of size or installation, cannot be readily transported to a machine shop for repair, are potable machining lathes such as shown in U.S. Pat. No. 4,739,685; 4,939,964; 5,685,996 and 5,549,024. When it is considered that air motors frequently do not provide the torque that is available from hydraulic motors and that at a given work site, one may not have the option of selecting one or the other to be used to drive the field machining tool, a need exists for a gearbox that can be mounted between the output shaft of either a hydraulic motor or an air motor and the input shaft of the machining tool to adapt either an air motor or a hydraulic motor as a power source for the machining tool. As an example, the gearbox 29 of the Ricci Pat. No. 4,939,964 is designed only to mate an air motor 28 to drive ring gear 15. If at a job site a suitable air supply were not available, but only an internal combustion engine-driven hydraulic pump and hydraulic motor were available, it would be necessary to substitute a different gearbox for the gearbox 29. Such a substitute may not be readily available.
It is accordingly an object of the present invention to provide a gearbox that can readily be modified at a worksite to offer either a gear train affording higher speed and lower torque for use with a hydraulic drive or a lower speed, higher torque for use with a pneumatic drive.
The present invention comprises a split frame gearbox for driving a metalworking tool from either a hydraulic motor or an air motor. It comprises a lower frame member of a generally rectangular box-like configuration having a bottom wall and a perpendicularly extending side wall defining a chamber with an open top. Removably affixed to upper edge of the side wall is an upper frame member. An input shaft is provided having an input gear thereon where the input shaft is journaled for rotation in a first bearing fitted into a first bore formed in an underside of the upper frame member. The input gear has a predetermined number of teeth, N1. The input gear is made to mesh with a first driven gear that is mounted on a jackshaft journaled in second and third bearings where the second bearing resides in a second bore on the underside of the upper frame member and the third bearing residing in a first bore formed on the bottom wall. The first driven gear has a predetermined number of teeth, N2, that is greater than N1. A second driven gear is keyed on the same jackshaft as the first driven gear and has a number of teeth, N3. The gearbox further includes an output shaft that is on a common axis with the input shaft and has a third driven gear keyed thereon where the third driven gear has a number of teeth, N4 that is greater than N3. The output shaft is journaled for rotation in a bearing disposed in a bore formed in an adaptor plate affixed to the bottom wall. By simply detaching the upper frame member, access can be had to the input gear and the first driven gear so that they can be replaced by gears offering a different gear ratio. With the upper frame member again screwed in place, the gear ratio of the split frame gearbox can be adapted to accommodate one or the other of an air motor or a hydraulic motor drive.
The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts.
This description of the preferred embodiment is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top” and “bottom”, “under”, as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, “underside”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “joined”, and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece unless expressly described otherwise.
Referring to
Visible in the perspective view of
Visible in the isometric view of
Bolted to the upper edges of the side walls 16-22 of the lower frame member 12 is an upper frame member 25.
Referring next to the cross-sectional view of
The spur gear 30 is designed to mesh with a first driven gear 34 that is keyed to a jackshaft 36 where the jackshaft 36 is journaled for rotation in a first bearing race 38 fitted into a bore formed in the undersurface of the upper frame member 25 and a bearing race 40 disposed in a bore formed in the bottom wall 14.
The jackshaft 36 also has a second driven gear 42 keyed to it.
The output shaft 28 resides on a common axis 44 with the input shaft 26 and it is journaled for rotation by a bearing race 46 at its upper end and a sleeve bearing 48 that is fitted into a bore formed through the adaptor plate 24. As seen in
Assuming that the input drive gear 30 has 24 teeth and the upper driven gear 34 has 48 teeth and, similarly, lower gear 42 on the jackshaft 36 has 24 teeth and the gear 50 on the output shaft has 48 teeth, the gearbox 10 provides a 4 to 1 gear ratio which provides an optimal torque if an air motor is being used as the prime mover. One can easily convert the gearbox 10 to offer a 2 to 1 ratio if hydraulic power is to be used. To do so, one need only unscrew and remove the upper frame member 25 to gain access to the gears 30 and 34. By removing them and replacing them with gears each having 36 teeth, a desirable 2 to 1 ratio is achieved when a hydraulic motor is to be used as the prime mover. This modification can be made in a matter of a few minutes.
Those skilled in the art will appreciate that using a 4 to 1 ratio allows an air motor to climb higher into the RPM range due to the load being reduced. This, of course, provides an increase in torque. By converting to a 2 to 1 ratio, the gearbox 10 closely matches the torque requirements required when utilizing hydraulic power.
It can be seen, then, that the gearbox of the present invention allows one to obtain the optimum range of speed and torque when using either an air motor or a hydraulic motor as the prime mover. It is only a simple matter to remove the upper frame member 25 and substitute gears of appropriate number of teeth for input gear 30 and the first driven gear 34.
This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices. Also, various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.
