Patent Application
20140147208
This invention relates generally to boat hoists and more particularly to a boat hoist for use on piling posts secured to the bottom of the body of water and/or boat houses built on such pilings.
Hydraulically actuated boat hoists are shown in U.S. Pat. Nos. 6,823,809 to Hey, 6,976,442 to Hey 7,246,970 to Hey, 7,413,378 to Way and 8,267,621 to Way, all of which are incorporated herein by reference in their entirety.
Southern U.S. States and coastal regions commonly use one of these three methods to store/moor boats: (1) Moor the boat to a fixed or floating pier using ropes. In this case, the boat remains in the water, (2) lift the boat using a platform or sling type lift mounted to a set of pilings or roof structure mounted on pilings, or (3) lift the boat using a floating lift system. The most common method used depends on the region and regulations governing the body of water. Many reservoirs do not allow private ownership of waterfront property. In these lakes, there tends to be large marinas or “dockominum” structures. In these structures in-water mooring is the most common. A small percentage of the boats are lifted using a floating lift. Floating lifts are usually the only type allowed on a large dock structure. Marina managers discourage any structure being fixed to these floating systems.
Many lakes and waterways allow private waterfront ownership. In these cases, a permanent, fixed pier can be installed. Often a permanent roof structure is built over the slip intended for the boat commonly called a “boat house”. When these structures are present, a large percentage will have a mounted lift system. Some permanent docks do not have a roof structure. A lift is usually mounted on the top of large pilings when no roof is present.
Pile and roof mounted lift systems have been around for decades. The lift designs are basically the same. Galvanized poles are mounted in bearings hanging from a beam in the roof or a beam mounted along the pilings. A “plate-gear” motor is connected to the end of the pole that causes the entire pole to turn. Cables are attached to the pole and wind as the pole turns. In lower capacity, roof-mount applications, one pole can be used, but in pile mount applications and higher capacity roof-mounts, two poles and motors are used.
Some differentiation exists in the pole winding products. Some have improved on the motor and controls to included wireless operation. Some have added machined cable grooves to improve cable winding. There is even one company that uses a “level cable” technique to make a single motor/pole piling application. They also have some variation on the platform, bunks, and load guide features. Low-cost kits use a sling instead of a platform.
Pole-winders have many weaknesses that present opportunities. Cable fatigue, motor synchronization, slow speed, poor corrosion resistance, and power supply issues are a short list of issues with current products. Cable fatigue is in a guaranteed failure mode if cables are not replaced every 2-3 years, depending on frequency of use. All of the designs on the market use wire rope. The galvanized poles used in these designs cause rapid fatigue of the cables because of the small winding diameter. Compounding the issue is the large lift height requirement for most installations. It is common to lift the boat 6-10′ to accommodate the fluctuating water heights. This requires many winds on the pole and in most cases, the cable winds over itself. This not only fatigues the cable, but also damages the individual wires with the wire rope.
Cable failure modes are severe and cause the boat to fall in one direction endangering people and equipment. The most common approach to avoiding this failure is to replace cables often.
Motor synchronization is also an issue in multi-pole/motor setups. Piling mount systems have at least two motors because there is no overhead structure to route cables to a single pipe. The speed of the motors will vary causing one to lift faster or slower than the other. Most systems require the user to use a switch to momentarily shut off one of the motors to allow the slower motor(s) to catch up. This requires constant user attention when lifting or towering the boat. Compounding this issue is the slow speed of the pole winding systems. Some lifts can take over 6 minutes to lift the boat to the needed elevation above the water.
The galvanized construction of the pole winding systems is adequate for most environments, but they eventually rust as the wound areas of the poles lose their zinc coating. The bearing locations are generally welded components. Aluminum or other naturally corrosion resistant materials are avoided because of the high stresses in these areas. Cable materials are often galvanized also due to the high replacement rate. The cable will be replaced due to fatigue before corrosion becomes an issue.
Pole-winding systems are predominately A/C power systems. Piling mount systems require a long supply from the dock to the opposite motor. This can often be a 40-50′ length of cord to run down from the dock, tinder the water, and back up to the opposite motor. This length is too long for a DC (12-24V) power supply to run without extremely heavy wire. The length of the circuit from the supplying A/C panel to the motors is also very long. This often creates a large voltage drop along the circuit. The voltage drop can cause the system to malfunction and reduce the life of the motor(s) in the system. Often new installations require new circuits to be installed with heavier cable.
A/C power can be dangerous system in wet environments. GFCI (ground fault circuit interrupts) are and absolute requirement on docks. Many lives have been lost due to damaged A/C circuits causing stray A/C currents in lakes and waterfronts with inadequate circuit protection. Pole winding systems are commonly used primarily because they can be easily installed in most existing structures with little modification and they are inexpensive when compared to floating or free-standing lift designs.
The vast majority of floating lift systems are called “Air Displacement” systems. Air displacement systems raise and lower a lift structure using floats. The floats are filled with air that is evacuated to allow the structure to sink. The floats are then filled using vacuum pumps to raise the structure with the boat on it.
Floating systems such as U.S. Pat. No. 6,823,809 to Hey have a few advantages over free standing and mounted lift structures. They can be used in very deep water where pile mounted systems are not an option. They can also be used in dockominium structures where a very limited structural connection is available.
U.S. Pat. No. 6,823,809 to Hey shows a boat lift that mechanically lifts the boat using a unique linkage to lift the boat without requiring air evacuation. This hydraulic system is innovative, but expensive. The system also places critical hydraulic components at the waterline. This jeopardizes the durability of the system. Those boat hoists do not require any structural connection to the pier and can be moored similarly to the boat.
But air displacement lifts require a mounted structure on the dock. As air is evacuated from the floats gravity will cause the structured to sink to the lakebed unless a structure is in place to limit the travel. This lift style does not work well in shallow areas because of the size of the floating structure.
Lift capacity of floating lift systems is determined by the amount of flotation. The float structure is also designed to allow the structure to lift the boat sufficiently above the water. As the lift capacity increases, the number of air chambers increases. Larger structures require the user to evacuate the chambers at different rates to ensure a balanced movement. Users often complain about this requirement and the difficulty controlling it.
U.S. Pat. Nos. 6,976,442 to Hey and 7,246,970 to Hey show boat lifts that use a cantilever method to lift the platform. The lift will be in the elevated position most of the time, so that in these systems, the rod surface spends most of its life exposed to the harsh marine environment. This can cause corrosion and pitting of the rod surface which will cause leaking of the hydraulic seals.
Accordingly, there is a need for a boat lift for pilings and boat houses that will overcome the aforementioned problems.
The present invention relates to a hydraulic lift system is a roof or pile-mounted lift system. The unique design uses a pair of hydraulic cylinders to pull a system of lift cables. The cable system is strung through a tube with large diameter sheaves. This design totally eliminates the cable fatigue caused by winding cables.
The hydraulic lift of the present invention is very fast 6-8 times faster than the equivalent pole winding system. The heart of the system is a tandem hydraulic power unit that creates an equal volume flow into both lift cylinders. This equal volume ensures level lifting no matter how the load is balanced on the tilt platform.
One aspect of the hydraulic system of the present invention eliminates the need to run A/C power under water to other motors. The pressure from the hydraulic power unit can be delivered to multiple cylinders through hoses that can be run under water or overhead if a roof structure exists. This allows DC power to be used and eliminates the burden on the A/C supply circuit. Using a volume-leveling hydraulic system eliminates the user intervention required by multi-motor systems. Any out of synchronization that occurs is automatically corrected at the end of the lifting process with a unique pair of switches wired in parallel. This makes everyday operation fast and user friendly.
The retracting motion of the hydraulic cylinder causes the lift to rise. Boats spend the majority of the time lifted in a stored position. The lift cylinders will be retracted most of the time, protecting the rod surface from the elements. This is unique compared to other hydraulic lift systems that extend the cylinder to cantilever a lift platform. In these systems, the rod surface spends most of its life exposed to the harsh marine environment. This can cause corrosion and pitting of the rod surface with will cause leaking of the hydraulic seals, but the preferred embodiment of the present invention is immune to this type of corrosion because of the lifting principle used with the hydraulic cylinders being retracted in the raised position of the lift.
The hydraulic system is designed to allow fluid ‘bypass’ when a lift cylinder reaches the end of its stroke. This allows the lift cylinders to automatically ‘level up’. If one cylinder fully retracts before the other, the hydraulic power unit can continue to retract the other cylinder. This auto-level function eliminates the need for a user to manually level the lift using switches to control individual motors.
The above mentioned advantages are at least partially met through provision of the method and apparatus described in the following detailed description, particularly when studied in conjunction with the drawings, wherein:
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.
Referring now to the drawings, wherein like reference numerals designate identical or similar parts throughout the several views,
The boat lift (1) shown in
A boat lifting platform (12), shown in
Flexible lines or cables (16), (18), (20) and (22) extend from the platform (12) upwardly to mechanisms within the elongated lift tubes/elongated members (10) and (11), the mechanisms being shown in detail in
A hydraulic cylinder (14c) is attached at one end to the elongated member (11) by a pin (11p) that extends through the tube (11), through openings in flanges (14f) of hydraulic cylinder (14c) and through an idler pulley (36).
The rod (14r) of the hydraulic cylinder (14c) has a pulley block (34) attached thereto and flexible lines or cables (20) and (22) are trained around respective idler pulleys (34), (35) and (36) as shown in
It will be appreciated by referring to
Referring again to
The hydraulic lines (43) and (44) shown in
In operation, the hydraulic boat lift would be in the lowered position shown in
As the boat cradle (12) is raised by shortening the hydraulic cylinder (14), a button (20b) will move upwardly towards a normally closed switch (50) as shown in
Those skilled the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept as expressed by the attached claims.
