Method and apparatus for jackscrew with integral drive nut grease fitting

Abstract

An improved device and method of lubrication for a tongue jack, 5th wheel jack, or other jack or other threaded positioning device. Ports are provided in the inner and outer tubes of the jack. The aligned ports provide access to a lubrication cavity in the jacknut. The lubrication cavity may include a grease fitting such as a zerk fitting. When the ports are in alignment, a grease gun can be inserted easily to the zerk fitting to apply grease to the interior structure of the nut as well as to the threads of the jackscrew. The lubricant may be introduced directly at a region of contact between a screw and the load bearing element. Applicant's test results show that this improved lubrication can increase the life cycle of the jack by more than 100%.

Claims

1. A jackscrew assembly comprising an outer tube assembly comprising an outer tube with an outer tube access port; an inner tube assembly, slidable with respect to the outer tube assembly, the inner tube assembly comprising an inner tube comprising an inner tube access port, a threaded jack drive nut fixed relative to the inner tube, the jack drive nut comprising a recessed lubrication cavity, the lubrication cavity comprising a grease fitting such that the inner tube access port is aligned with the lubrication cavity grease fitting, and a jackscrew threaded through the jack drive nut, such that the outer tube access port is configured to be alignable with the inner tube access port in order for a lubricant to be applied to the lubrication cavity grease fitting.

2. The jackscrew assembly of claim 1 wherein the grease fitting is a zerk fitting.

3. The jackscrew assembly of claim 1 wherein the jack drive nut engages a plurality of ball bearings.

4. A trailer jack comprising a jackscrew assembly comprising an outer tube assembly comprising an outer tube with an outer tube access port; an inner tube assembly, slidable with respect to the outer tube assembly, the inner tube assembly comprising an inner tube comprising an inner tube access port, a threaded jack drive nut fixed relative to the inner tube, the jack drive nut comprising a recessed lubrication cavity, the lubrication cavity comprising a grease fitting, such that the inner tube access port is aligned with the lubrication cavity grease fitting, and a jackscrew threaded through the jack drive nut, such that the outer tube access port is configured to be alignable with the inner tube access port in order for a lubricant to be applied to the lubrication cavity grease fitting; and a manual or electric jackscrew drive.

5. The jack of claim 4 wherein the grease fitting is a zerk fitting.

6. The jack of claim 4 wherein the jackscrew drive is manual.

7. The jack of claim 4 wherein the jackscrew drive is an electric motor.

8. The jack of claim 4 wherein the jackscrew drive is part of a tongue jack.

9. A method of lubricating a jackscrew assembly comprising an outer tube, an inner tube assembly with an inner tube, a jack drive nut with a wall and interior threads, the jack drive nut fixed relative to the inner tube, and a jackscrew with threads which are threaded through the jack drive nut, the method comprising providing a recessed lubrication cavity on the jack drive nut, the lubrication cavity comprising a grease fitting: providing an inner tube access port on the inner tube, such that the inner tube access port is aligned with the lubrication cavity grease fitting: providing an outer tube access port on the outer tube; aligning the inner tube access port with the outer tube access port; and applying a lubricant through the wall of the jack drive nut to the recessed grease fitting, thereby applying the lubricant to the threads of the jackscrew and interior threads of the jack drive nut.

10. The jack of claim 4 wherein the jackscrew drive is part of a 5th wheel jack.

11. The method of claim 9 further comprising providing a zerk fitting in the lubrication cavity.

Description

DESCRIPTION OF FIGURES

(1) FIG. 1 is a side cross section view of a prior art jackscrew.

(2) FIG. 2A is a side view of a jackscrew assembly comprising an outer tube assembly and an inner tube assembly.

(3) FIG. 2B is a cross section view of the upper portion of the jackscrew assembly of FIG. 2A showing a jackscrew.

(4) FIG. 2C is a detailed cross section view of aligned access ports in the outer tube and inner tube of the jackscrew assembly of FIG. 2A to provide access to a grease fitting in the jack drive nut.

(5) FIG. 3A is a side view of the inner tube assembly of the jackscrew assembly of FIG. 2A.

(6) FIG. 3B is a cross section view of the upper portion of the inner tube of FIG. 3A.

(7) FIG. 3C is a detailed view of the top of the inner tube of FIG. 3B showing the inner tube access port and the grease fitting.

(8) FIG. 4A is a front view of an electric tongue jack with a motor gear assembly and the jackscrew assembly of FIG. 2A.

(9) FIG. 4B is a side view of the electric tongue jack of FIG. 4A.

(10) FIG. 5 is a side perspective view of a trailer electric tongue jack comprising a motor gear assembly and a lower stem assembly.

(11) FIG. 6 is an exploded view of the motor gear assembly of the electric tongue jack of FIG. 5.

(12) FIG. 7 is an exploded view of the lower stem assembly of the electric tongue jack of FIG. 5.

(13) FIG. 8A is an exploded view of jackscrew assembly for a 5th wheel jack, comprising an outer tube assembly and an inner tube assembly.

(14) FIG. 8B is a cross sectional view of the inner tube, jackscrew, jack nut, and inner tube access port for the 5th wheel jackscrew assembly of FIG. 8A.

DETAILED DESCRIPTION OF EMBODIMENT—JACKSCREW WITH GREASE FITTING IN JACK Drive Nut

(15) The following example element list is provided for convenience in referencing the figures.

(16) TABLE-US-00001 Element list electric tongue jack 101  motor gear assembly 400  lower stem assembly 300 jackscrew assembly 200  outer tube assembly 220   outer tube 230    outer tube access port 232  inner tube assembly 240   inner tube 242     top 243    inner tube access port 244   jack drive nut 250    jack drive nut top 251     lubrication cavity 252      grease fitting 254   jackscrew 260 5th wheel jack jackscrew assembly 201  outer tube assembly 221   outer tube 231    outer tube access port 233  inner tube assembly 241   inner tube 245    inner tube access port 248   jack drive nut 255    lubrication cavity 256     grease fitting 259   jackscrew 261  washer 510  ball bearings 520  shaft pin 522  support 540  clip 542  pin 544

(17) FIG. 2A is a side view of a jackscrew assembly 200 comprising an outer tube assembly 220 and an inner tube assembly 240. An outer tube access port 232 is provided in the outer tube assembly for applying a lubricant to the jacknut, such as by greasing a zerk fitting 254.

(18) FIG. 2B is a cross section view of the upper portion of the jackscrew assembly 200 of FIG. 2A showing a jackscrew 260.

(19) FIG. 2C is a detailed cross section view of the outer tube 230, an inner tube 242, a jack drive nut 250 with a grease fitting 254, such as a zerk fitting, provided in a lubrication cavity 252. In this embodiment, the nut grease fitting recess 252 is fixed relative to an inner tube access port 244. When the inner tube access port 244 is aligned with the outer tube assembly access port 232, the orientation permits grease or other lubricant to be applied directly to the jacknut. In this example, the lubricant is grease which is applied through the grease fitting 254 at the region of maximum stress and wear in the jackscrew assembly.

(20) FIG. 3A is a side view of the inner tube assembly 240 of the jackscrew assembly 200 of FIG. 2A. FIG. 3A shows the inner tube 242, inner tube access port 244, and the top 251 of the jack drive nut 250.

(21) FIG. 3B is a cross section view of the upper portion of the inner tube 242 and jack nut 250.

(22) FIG. 3C is a detailed view of the top of the inner tube 242 and the jack nut 250 showing the inner tube access port 244 and the grease fitting 254. In other examples, the grease fitting 254 may be omitted, and the drive nut includes a lubrication cavity 252 where oil, dry graphite, or other lubricant may be introduced to lubricate the jack nut. This lubrication cavity is in communication with the jackscrew, such as with an orifice or lubrication channel that permits the lubricant to reach the jackscrew.

(23) FIG. 4A is a front view of an electric tongue jack 101 with a motor gear assembly 400 and the jackscrew assembly 200 of FIG. 2A.

(24) FIG. 4B is a side view of the electric tongue jack of FIG. 2A.

Example—Electric Tongue Jack with Grease Fitting in Jack Drive Nut

(25) FIG. 5 is a side perspective view of an electric tongue jack 102 for a trailer comprising a motor gear assembly 400 and a lower stem assembly 300.

(26) FIG. 6 is an exploded view of the motor gear assembly 400 of the electric tongue jack of FIG. 5.

(27) FIG. 7 is an exploded view of the lower stem assembly 300 of the electric tongue jack of FIG. 5.

(28) In this example, the jackscrew is lubricated by extending the jack until the zerk grease fitting is aligned with the access port in the outer tube. Using a standard grease gun, one or more pumps of grease are applied through the grease fitting.

Example—Manual Tongue Jack with Grease Fitting in Jack Drive Nut

(29) In this example, the electric drive of the previous example is replaced with a manual crank. Lubrication is provided as described above by aligning the outside tube access port with the grease fitting.

Example—5th Wheel Jack

(30) FIG. 8A is an exploded view of a 5th wheel jackscrew assembly 201 for a 5th wheel jack. The outer tube assembly 221 comprises an outer tube 231 with an outer tube access port 233. The inner tube assembly 241 comprises inner tube 245 with an inner tube access port 248 which provides access to grease fitting 259 positioned in lubrication cavity 256. Other elements in the 5th wheel jackscrew assembly include washer 510, ball bearings 520, shaft pin 522, support 540, clip 542, and pin 544.

(31) FIG. 8B is a cross sectional view of the inner tube 245, jackscrew 261, jack drive nut 255, and inner tube access port 248 for the 5th wheel jackscrew assembly of FIG. 8A.

(32) In this example, a grease fitting 259 is provided in lubrication cavity 256. When the inner tube access port 248 is aligned with the outer tube access port 233, the grease fitting is accessible.

(33) Method of Lubrication

(34) In one example, a jack is lubricated before leaving the factory. Under normal conditions, lubrication will be needed periodically, such as annually.

(35) A lubricant can be applied to the jackscrew by extending the inner tube by means of operating the motor or manually rotating crank until the port in the outer tube is aligned with the port in the inner tube. This alignment exposes the grease fitting or lubrication cavity.

(36) Once the ports are in alignment, grease or other lubricant can be applied through a grease gun or other lubricant application device directly to the inner threads of the threaded nut and the jackscrew threads. One means of lubricant application can be accomplished by use of a standard grease gun through a grease fitting or zerk in the threaded nut by one or more pumps of the grease gun.

(37) It is to be understood that the specific embodiments and examples described above are by way of illustration, and not limitation. Various modifications may be made by one of ordinary skill, and the scope of the invention is as defined in the appended claims.