Patent Application
20190337493
An improved device and method for lifting or jacking a vehicle is provided. In one embodiment, the device consists of a plurality of legs that are mounted directly to the axle(s) of a vehicle. The legs vary in length and are free to rotate about an axis (pivot axis) from a fully retracted or stowed position to a fully extended position. When not in use, the legs are stored in the stowed position. When needed for lifting (jacking) the vehicle, the legs are released from the stowed position and allowed to rotate about their pivot axis until they come into contact with the ground. The shortest leg length is determined by the vehicle wheel diameter, without a tire, and the longest leg length is determined by the vehicle fully-inflated tire diameter. The shortest leg length is sized such that if the vehicle were resting on the rim of the vehicle wheel, the angle of the leg relative to the ground (leg angle) is steep enough that as the vehicle is moved along the ground plane, sufficient force is imparted on the leg such that the static friction between the leg and the ground surface prevents the leg from sliding relative to the ground. This angle is referred to as the “grip angle” and in this condition, the leg is said to be “engaged”. Once engaged, a jacking force is imparted on the axle which lifts (jacks) the vehicle. As the vehicle continues to move along the ground plane, the engaged leg continues to rotate about its pivot axis and continues to lift (jack) the vehicle as it rotates. The longest leg length is sized such that if the vehicle were fully lifted (jacked) with the longest leg in its fully extended position, there is sufficient ground clearance to facilitate removal and installation of the vehicle wheel having a fully inflated tire. Additionally, there is a plurality of legs of varying lengths, said lengths varying between the shortest leg length and the longest leg length such that as the vehicle is moved along the ground plane during the vehicle jacking process, at least one leg is always engaged. To jack the vehicle, simply release the legs from their stowed position which allows them to rotate about their pivot axis and come into contact with the ground causing the first leg to be positioned at a leg angle greater than or equal to its grip angle causing the leg to be engaged. Then, simply move the vehicle along the ground plane by pulling it forward or backing it up. As the vehicle continues to move along the ground plane, the engaged leg will continue to rotate, jacking the vehicle, until the leg reaches its fully extended position at which point the next leg reaches its grip angle, becomes engaged, and continues jacking the vehicle. This process continues progressively with each leg until the vehicle is completely jacked and the last leg (longest leg) is in its fully extended position. The device and method is extremely quick, easy and safe to use. Additional embodiments include but are not limited to; optional methods of attaching the device to the vehicle, optional locations for attaching the device to the vehicle, and optional means of causing the legs to rotate about their pivot axis.
Although this “Background” is written primarily with references to trailers, other vehicle types can have the same or similar issues, hazards, and challenges with respect to lifting or jacking the vehicle. This “Background” is not intended to be limited to trailers, but is intended to encompass any vehicle that may have a need to be lifted or jacked.
Trailers can be very difficult and potentially dangerous to jack, especially when they are fully loaded. Additionally, many trailers are not designed to properly handle jacking loads that can be imparted on them during the jacking process. This can damage the trailer as well as present significant danger to someone that is working on or around a trailer while it is jacked.
The primary reason for this difficulty is that most trailers do not have an adequate jacking location that is sufficiently designed to engage a jack nor is it sufficiently designed to properly handle jacking loads. As a result, once jacked, there is potential for the trailer to be damaged or to fall off of the jack. Most trailers are not sufficiently designed or made for assured safety and proper load distribution while being jacked.
This difficulty presents real problems for anyone that uses a trailer. If a business uses a trailer to transport equipment and materials for their business, a flat tire can delay their progress for several hours. Not only is it a logistical problem for delivering equipment, goods and materials to the intended customer or job site, there is significant potential for damage to the trailer as well as the equipment, goods and materials being transported, not to mention the potential safety hazards and danger affecting the personnel responsible for fixing the flat tire while traffic speeds by. This not only costs the business money, it exposes their personnel to danger and causes delays in providing product and services to the customer. The same issues face an individual using a trailer for personal or recreational use. Not only is there potentially significant inconvenience to the individual, there is a real potential for damage to the trailer and anything being hauled by the trailer and the individual is exposed to the same hazards and dangers associated with trying to jack a trailer on the side of the road while traffic speeds by.
Another problem or issue facing trailers is the amount of time many trailers sit idle, especially when loaded. Trailers that haul heavy equipment sometimes sit long periods of time with equipment loaded on them. Boat trailers are another example of trailers that are likely to sit idle for long periods of time while loaded. This is hard on the tires and can cause them to slowly leak air and go flat. It can also lead to other types of tire problems such as sidewall damage and tire dry rot.
Finally, another problem or issue facing trailers is the potential for theft, especially if they are loaded with some type of valuable cargo or equipment. There are devices currently available to provide security against theft, but with each of them, once the security device has been destroyed and removed, the trailer can easily be hooked up to a vehicle and stolen.
There are multiple examples of prior art that have attempted to address some of these issues. Hampson discloses in U.S. Pat. No. 829,333 a jacking device that consists of a jacking leg and utilizes vehicle motion for actuation. There are many other examples of prior art that offer variations to this approach. King discloses in U.S. Pat. No. 3,652,056 a jacking device that also utilizes vehicle motion for actuation, but adds an additional leg to the jacking device. The King jacking device contains a starter leg and a main support leg joined by a flexible member such that the main support leg is controlled by the attitude of the starter leg. Although this approach improves upon other prior art devices that utilize vehicle motion for jack actuation, the King approach does not provide adequate jacking range to provide complete jacking of a trailer having a completely flat tire or a trailer having completely lost its tire, especially for trailers or vehicles with smaller diameter wheels and larger diameter tires. Additionally, the King approach requires the use of a flexible member in order to control the main jacking support leg. as well as the use of a jack frame for attaching the jacking device to the trailer. Bollinger discloses in U.S. Pat. No. 3,733,051 and Jacobson discloses in U.S. Pat. No. 5,215,289, jacking devices that mount either on the trailer axle or some other similarly oriented cross member on the trailer. Both of these approaches cantilever the jacking leg between its mounting position on the trailer and the trailer axle or cross member. This approach is susceptible to inducing high loads from the jacking leg member into the axle or cross member during the jacking of the trailer. As the vehicle is moved to provide the jacking force and once the trailer is fully jacked and the jacking leg is resting against the axle or cross member, any further movement of the vehicle will induce extremely high cantilever loads which will potentially damage the axle, trailer, or jacking device. There are multiple other prior art examples that utilize movement of the vehicle to actuate a single jacking leg member such that the trailer is lifted including; U.S. Pat. No. 9,494,275 B2, U.S. Pat. Nos. 6,053,477, 5,228,651, 3,951,383, 3,881,746, and 3,744,757. Colclasure discloses a different approach in U.S. Pat. No. 3,881,691 in which the jacking leg member is pulled into position by a cable or by some other means other than by movement of the vehicle. One common drawback of the above prior art examples is that they do not provide sufficient lateral support for the trailer during the jacking process. Especially for situations in which a heavily loaded trailer is sitting on a sideward incline, later loads will cause the trailer to move laterally, perpendicular to the trailer jacking motion direction. Without sufficient lateral support, the trailer can induce tremendous side loads on the prior art jacking devices that can damage the trailer or the jacking device and can be extremely dangerous. Additionally, the prior art does not provide for a means of providing varying jacking positions simultaneously on each side of the trailer to account for uneven terrain.
The disclosed invention addresses all of the above challenges, problems and issues associated with jacking a trailer or any other vehicle that needs to be jacked and addresses the shortcomings of the prior art. It also addresses the challenges, problems, and issues associated with leaving a trailer sitting for extended periods of time and it can provide additional security and theft protection. This invention will help reduce down time in the event of a flat and will help improve safety for those that are faced with having to jack a trailer on the side of the road.
Although the described and illustrated embodiments have been in connection with lifting or jacking a trailer, it should be understood that the device is in no way limited to use with trailers. In fact, the device may be implemented to lift or jack virtually any vehicle type including automobiles, trucks, semi-tractor trailers, etc. and the device may be utilized to provide jacking or lifting of objects other than vehicles whether the objects have wheels or not.
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The preferred embodiment attaches to a vehicle in such a fashion as to allow a plurality of leg members to rotate relative to one another and about an axis. The geometry of each leg member is such that any lateral forces or loads acting perpendicular to the plane in which the leg member rotates (i.e. loads parallel to the rotation axis) are reacted by the leg member at the attachment to the rotation axis providing lateral stability during the jacking process and when in the fully jacked position. Additionally, the quantity of leg members and the geometry of leg members is such that regardless of the tire inflation condition, whether fully inflated or completely flat, one leg member will always rest against the ground plane at a steep enough angle (grip angle) to create enough downward force through the leg member and to the ground that sufficient static friction between the leg member and the ground will prevent the leg member from sliding relative to the ground such that when the vehicle is translated or moved along the ground plane, the leg member will become “engaged” and be caused to rotate about the axis providing a lifting force to the vehicle. When the vehicle is not in need of being jacked, the device is held in a stowed position such that it is out of the way and provides sufficient ground clearance as the vehicle travels down the road. When it is determined that it is necessary or desirable to jack the vehicle, the leg members are released from their stowed position and allowed to freely rotate about the axis until they come to rest against the ground causing one of the leg members, as a function of the amount of tire inflation, to be located at the appropriate grip angle and become engaged. Once in this “ready to jack” position, the vehicle operator moves the vehicle along to the ground plane. As the vehicle moves relative to the ground along the ground plane, the engaged leg member, located at its grip angle, will begin the jacking process and will begin to lift the vehicle. Once the first engaged leg member is in its fully extended position, its rotation is limited by the limiting member. As the vehicle continues along the ground plane and as each engaged leg member reaches its fully extended position (against the limiting member), each subsequent leg member will in turn be brought to its grip angle and will become engaged, continuing to lift the vehicle. This process continues through as many leg members as are required to bring the vehicle into the fully jacked position (with all leg members against the limiting member and locked in place by the locking member) such that a fully inflated tire is completely off the ground with sufficient clearance to allow changing of the tire.
Although a detailed description of the preferred embodiment has been disclosed, it is understood that other applications and embodiments are possible and that various changes, substitutions, modifications and/or combinations of the embodiment are possible without departing from the spirit of the invention including, but not limited to variations in leg member lengths and shapes, variations in means for locking the legs in the retracted position, variations in means for locking the legs in the extended position, variations in means of preventing leg members from rotating relative to one another, variations in means for attaching to the vehicle, variations in location of attachment to the vehicle (i.e. locations other than vehicle axle) as well as addition of other members, such as but not limited to foot members, spring members and actuating members that may aid in the extension and/or retraction of the leg members or otherwise improve the utility, function and use of the invention.
For each of the described configurations, it is also possible to move the ground plane relative to the vehicle being jacked and achieve the same effect.
Additionally, the vehicle or object being jacked does not have to have wheels for any of the described configurations to work. Similar configurations can be utilized to provide lifting or jacking of objects other than vehicles whether the objects have wheels or not.
