Patent Application
20110067513
The present invention relates to rotating turret systems, and in particular to gear boxes for rotating turret systems.
HMMWV 1 includes rotating turret assembly 2. Rotating turret assembly 2 includes .50 cal machine gun 3. To operate .50 cal machine gun 3, soldier 4 stands up within HMMWV 1 and stands behind armored shield 5 as shown. The soldier can fire machine gun 3 and receive armored protection from the armament of HMMWV 1 and armored shield 5.
During combat and during patrol it is important to be able to have the ability to aim machine gun 3 in a full 360 degree pattern so that the gunner can protect himself and the other soldiers in the HMMWV and nearby. Hence, turret assembly 2 is fully rotatable allowing 360 degree coverage.
Unfortunately, there is a very high rate of failure of turret assembly 2 during combat and patrol. An armored turret assembly (including armored shield 5) can weigh over 500 pounds. During combat, the soldier operating hand crank 7 turns it quickly to get into the appropriate position. This puts tremendous strain on the teeth of meshing gears 8 and 18. Such a situation is obviously hazardous when, for example, the operator is attempting to maneuver a turret mounted weapon into firing position, especially when HMMWV 1 is on an incline (
To test prior art gear box 25 a new prior art gear box 25 was attached to turret assembly 2 as shown in
What is needed is a better gear box assembly for turret assemblies.
The present invention provides a gear assembly for retrofitting a rotatable turret assembly having pre-existing mounting brackets. A gear assembly housing is fabricated so that it fits onto the pre-existing housing mounting brackets. An operator controlled hand crank is connected to an input shaft. The input shaft extends through the gear assembly housing and includes an input shaft gear that meshes with a drive shaft gear. The size of the drive shaft gear has been maximized so that it fits within the gear housing that has been mounted on the pre-existing mounting brackets. A drive shaft is connected to the drive shaft gear and extends through the gear housing. A sprocket is connected to the end of the drive shaft gear. The sprocket is mechanically linked to the turret assembly for controlling the rotation of the turret assembly. In a preferred embodiment, the turret assembly is mounted to a HMMWV. Also, in a preferred embodiment the gear housing is fabricated from 6061 billet aluminum and includes cuts to allow for a maximum sized drive shaft gear.
Preferred gear box assembly 50 is shown in
As explained in the Background section, prior art gears 8 and 18 fail during normal combat usage. To solve the problem of gear failure, the gear box assembly uses larger gears 55 and 60. Housing unit 57, and end caps 58 and 59 are fabricated from high quality aircraft grade 6061 billet aluminum. Also, the utilization of end caps 58 and 59 allows for gear box assembly 50 to be easily taken apart for routine maintenance.
Drive gear 55 is a spiral bevel gear. In the prior art gear box, drive gear 8 suffers failure primarily because of its size. It is therefore the goal of the present invention to make drive gear 55 as large as possible within the confines set up by mounting brackets 52. In a preferred embodiment of the present invention drive gear 55 is approximately 1.86 inches in diameter.
Table 1 summarizes a preferred drive gear 55:
Input gear 60 meshes with drive gear. Input gear 60 is attached to input shaft 62.
Input shaft 62 is supported by bearings 63 and 64. Bearings 63 and 64 are separated by approximately 1.5 inches to allow for optimum support. The distance of 1.5 inches reduces torsional stress on input shaft 62. Snap ring 65 helps hold bearing 64 in place and seal 66 seals housing 57.
Coupler 67 and adapter 68 fit on input shaft 62. Adapter 68 attaches to prior art crank 7 (
Drive shaft 70 extends through housing 57 and is supported by bearings 71 and 72. Bearing 71 fits into end cap 58 and bearing 72 fits into end cap 59. Seal 73 is adjacent bearing 72 and seals drive shaft 70 within housing 57. Drive gear 55 is connected to drive shaft 57 as shown.
Gear housing 57 and end caps 58 and 59 are all fabricated from 6061 billet aluminum. 6061 billet aluminum provides the optimum balance of hardness and strength to reduce unnecessarily torsional stress and wear on the gears. End caps 58 and 59 are both bolted to gear housing 57 (
It should also be noted that the utilization of 6061 billet aluminum allows the utilization of very large drive gears. For example,
Drive sprocket 95 is connected to the end of drive shaft 70. Drive sprocket 95 is further held in place by utilization of bolt and washer 96.
To test the preferred embodiment, gear box assembly 50 was attached to turret assembly 2 as shown in
In the preferred embodiment described above, gear box assembly 50 has a load rating of 148 inch-pounds. This is a 100% increase in strength over prior art gear box 25.
A significant advantage of gear box assembly 50 is that it is very easy to repair existing HMMWV's currently in operation. There is no need to replace the entire turret assembly, only the gear box assemblies need replacement. Also, drive gear 55 is larger and will last much longer than the prior art drive gear. Finally, when it is determined that it is appropriate to replace drive gear 55, it can be replaced easily by removing end caps 58 and 59 as discussed above. Drive gear 55 can be inspected and replaced if necessary, without having to replace the entire gear box assembly 50.
Although the above-preferred embodiments have been described with specificity, persons skilled in this art will recognize that many changes to the specific embodiments disclosed above could be made without departing from the spirit of the invention. Therefore, the attached claims and their legal equivalents should determine the scope of the invention.
