Trailer support arrangement

The invention provides a supporting arrangement for a trailer that is towable by a vehicle, in which the trailer includes a tongue for connecting the trailer to the vehicle. The supporting arrangement includes a tongue jack mounted on the tongue. In a deployed position, the tongue jack vertically supports the tongue and thereby prevents contact between the tongue and the ground. In a retracted position, the supporting arrangement holds the tongue jack clear of the ground. A motion detection arrangement senses a dangerous trailer configuration, in which the tongue jack is in the deployed position and actual or potential motion of the trailer above a safe speed is present, and then activates a retraction assembly that automatically moves the tongue jack from the deployed to the retracted position upon activation of the release mechanism. A manual activation arrangement is preferably also included for allowing activation of the release mechanism by a user. In the preferred embodiment of the invention, the retraction assembly includes a solenoid that is able to release a pressurized gas cylinder that, upon extension, urges the tongue jack into the retracted position and that is re-pressurized by manual movement of the tongue jack into the deployed position.

FIELD OF THE INVENTION
 This invention relates to an arrangement for use with various types of
 trailers that have a tongue by which a vehicle can tow the trailer, and a
 tongue jack arrangement that supports the trailer when it is disconnected
 from the towing vehicle.
 BACKGROUND ART
 Trailers such as cargo trailers, camping trailers, boat trailers and the
 like that are used with automobiles and small trucks are often single-axle
 or bogie trailers that are towed via a tongue (also known as a "drawbar")
 that is connected to or integral with the chassis of the trailer. The
 tongue typically has a single-beam or wishbone structure, depending on the
 load the trailer is to carry. When the trailers are disconnected from the
 vehicle, a tongue jack is arranged mainly near the front part of the
 tongue to support the tongue so that it will not rest with its hitch on
 the ground, and also so that the trailer will stand mainly parallel to the
 ground to make for easier loading and unloading.
 The tongue jack is commonly designed as a threaded rod within a tube so
 that a supporting wheel or plate can be cranked down to the ground when
 the trailer is unhitched, or up when it is hitched and ready to be towed.
 For some trailers, the tongue jack is often removably or pivotably mounted
 on the tongue by means of a bracket. When the bracket is removed or the
 jack pivoted up, the jack can be locked clear of the ground and the
 trailer can be safely towed.
 A common problem is that many people forget to retract and lock the tongue
 jack when the trailer has been hitched to a towing vehicle. When the
 vehicle then drives away, the tongue jack will sooner or later catch on
 the ground or road with the result that the entire tongue jack arrangement
 is deformed or, in the worst case, torn off.
 What is needed is an arrangement for tongue jacks that eliminates this
 risk.
 SUMMARY OF THE INVENTION
 The invention provides a supporting arrangement for a trailer that is
 towable by a vehicle, in which the trailer includes a tongue for
 connecting the trailer to the vehicle. The supporting arrangement includes
 a tongue jack mounted on the tongue. In a deployed position, the tongue
 jack vertically supports the tongue and thereby prevents contact between
 the tongue and the ground. In a retracted position, the supporting
 arrangement holds the tongue jack clear of the ground.
 A retraction assembly is provided, which includes a release mechanism, and
 which moves the tongue jack from the deployed to the retracted position
 upon activation of the release mechanism. A motion detection arrangement
 is also provided for sensing a dangerous trailer configuration, in which
 the tongue jack is in the deployed position and actual or potential motion
 of the trailer above a safe speed is present, and for activating the
 retraction means and thereby the release mechanism upon sensing the actual
 or potential motion. A manual activation arrangement is preferably also
 included for allowing activation of the release mechanism by a user.
 In the preferred embodiment of the invention, the retraction assembly
 includes an electrically activated, movable member (such as the core of a
 solenoid) that activates the release mechanism when the dangerous trailer
 configuration is sensed. A control rod is preferably included for
 transmitting motion of the movable member to the release mechanism.
 Furthermore, in the preferred embodiment, the retraction assembly includes
 a pressurized gas cylinder that is connected to the tongue jack and that,
 upon extension, urges the tongue jack into the retracted position and that
 is re-pressurized by manual movement of the tongue jack into the deployed
 position.
 The motion detection arrangement preferably includes a switch, located in
 the vehicle, that connects the retraction means with a voltage source in
 the vehicle and thereby activates the retraction means when the vehicle
 generates an electrical signal associated with impending or actual motion
 of the vehicle.

DETAILED DESCRIPTION
 In FIG. 1, a trailer and a towing vehicle are indicated generally by
 references numerals 100 and 102, respectively. The tongue of the trailer
 is indicated by reference numeral 104, and extends in a longitudinal
 direction, that is, the direction on which the trailer will move when
 towed. FIG. 1 is not drawn to scale solely in order to make it easier to
 see the various features of the invention, and how they work. In the
 description of the invention below, the terms "left," "right,"
 "clockwise," and "counter-clockwise" indicate directions and movements as
 viewed in FIG. 1.
 A tongue jack, indicated generally by reference numeral 106, includes a
 main vertical tube, shaft or support--a down tube 108--and a supporting
 wheel (often, a caster wheel) or plate arrangement 110 that can be cranked
 or pivoted down via the down tube 108 using a crank or handle 112.
 According to the invention, the tongue jack 106 is rigidly connected (for
 example, by welding), preferably via a reinforcing bracket or plate 114 to
 an axle 116, which extends transversely to the tongue 104 (perpendicular
 to the plane of FIG. 1). The axle 116 (which may already be included on
 the trailer to retract and deploy an existing tongue jack), is mounted in
 any conventional way on the tongue so that the jack can pivot clockwise
 and counter-clockwise. For single-beam tongues, the jack arrangement may
 be mounted to either side of the beam, or in a cut-out portion; for
 wishbone-shaped tongues, the jack arrangement is preferably mounted
 between the two arms.
 The trailer 100 is hitched to the vehicle 102 using any conventional
 arrangement. In FIG. 1, a common hitching ball arrangement is illustrated,
 in which a bracket 118 is placed onto and locked into place on a hitching
 ball 120.
 According to the invention, an energy-storing device is mounted on the
 trailer, near the jack arrangement 106 on the tongue 104. In the preferred
 embodiment, the energy-storing device is a gas cylinder or gas damper 122
 (or a combination of more than one such device, in order to increase the
 total extension power). The structure of such a gas cylinder is well
 known, for example, as a locking damper built into the pedestal of many
 modern office chairs. Gas cylinders such as the one preferably used in
 this invention typically either have a housing that "telescopes," that is,
 with at least one tube within another, or with a shaft that extends out
 from and retracts into the cylinder housing. This allows the cylinder as a
 whole to be lengthened and shortened, that is, to be extended and
 compressed. A locking or releasing mechanism such as a pin 124 is included
 in (typically, in the end of) the cylinder. When the pin (or other
 mechanism) depressed (or otherwise activated), then a piston or (other
 valve arrangement) within the cylinder housing is free to move and the
 cylinder can be extended or compressed. When the pin 124 is released, then
 the piston is prevented from moving and the cylinder "locks," that is, it
 strongly resists compression or extension. (In the invention, the cylinder
 preferably locks to become essentially rigid, unlike the cylinders used in
 chairs, which often become "springy." Cylinders of the rigidly locking
 type are commercially available.) In one working prototype of the
 invention, the gas pressure within the cylinder generated a compression
 force within the cylinder 122 of approximately 200 Newtons; when in the
 locked position (compressed, with no mechanical activation of the locking
 pin 124), the cylinder was able to hold roughly 1200 kg without extending.
 In the invention, the end of the gas cylinder 122 opposite the locking pin
 124 is pivotably connected to a lever arm 126, which is rigidly connected
 (for example, by welding) to the axle 116. Note that, if the downtube 108
 is already pivotable about an existing axle, then it would also be
 possible to attach the cylinder directly to the downtube. The connection
 between the end of the cylinder and the arm 126 (or downtube 108) is
 arranged in any conventional manner (for example, with a pin that can
 slide in a cut-out aligned in the arm and aligned with the arm, or by
 allowing the cylinder itself to pivot, or via some other pivoting bracket)
 to allow the arm 126 to rotate as the cylinder is extended and compressed
 in its mounted position.
 When the tongue jack arrangement 106 is deployed, that is, in its mainly
 vertical, deployed position (shown in FIG. 1), in which the wheel 110
 contacts the ground and the tongue jack supports the tongue of the
 trailer, the cylinder 122 is substantially fully compressed. When the
 locking pin 124 is depressed, the gas cylinder is freed to expand, which
 pushes the arm 126 to cause it, and thus the whole jack arrangement, to
 rotate counter-clockwise (as indicated by the arrow next to the wheel 110)
 until the jack arrangement reaches a mainly horizontal, retracted position
 in which it is completely clear of the ground. The length of the arm 126
 and the range of expansion of the cylinder are chosen using known design
 methods so that the jack arrangement is fully retracted when the cylinder
 is substantially fully extended.
 To deploy the jack arrangement 106, the user rotates it clockwise, thereby
 compressing the cylinder. Note that the moment arm provided by the
 downtube 108 will be much larger than that between the cylinder 122 and
 the axle 116, so that the user will be able to compress the cylinder with
 relative ease.
 The invention preferably provides for two separate ways--one manual and one
 automatic--to activate (cause to expand) the gas cylinder 122 by pressing
 the pin 124 (activating the release mechanism). A lever or handle 130 that
 is pivotably mounted on the tongue 104 (or at some other convenient
 position on the trailer) is used for manual retraction of the jack
 arrangement and an electromagnet--preferably a solenoid 140--is included
 to provide automatic retraction.
 One way to provide manual retraction is to mount the pivoted handle 130 in
 such a way that it, or some member attached to it, depresses the pin 124
 when the user moves the handle towards the pin. Similarly, automatic
 retraction can be provided by mounting the solenoid 140 so that its core
 shaft (or an extension mounted on the core shaft) pushes the pin when the
 core shaft is extended. In the preferred, illustrated embodiment of the
 invention, however, the handle 130 and solenoid 140 cooperate to activate
 the pin 124 via a cable 150.
 The cable 150 is preferably a sheathed, flexible control rod of a structure
 similar to control rods used to remotely activate camera shutter releases,
 or as brake cables on most bicycles. As is well known, such flexible
 control rods have a central, flexible rod 144, usually with a stopper tip
 146, 148 at either end. The central rod can slide freely within the outer
 sheath 152. In the preferred embodiment of the invention, the ends of the
 sheath 152 are secured in mainly vertical brackets or other supporting
 members 160, 162, through both of which the central rod 144 extends.
 One end of the central control rod 144 is preferably attached to the handle
 130, either rigidly or simply so that the central rod extends through the
 handle and is stopped by the stopper tip 146. The other end of the central
 control rod is preferably similarly attached to a pivoting arm 164, on
 which is a portion or protruding contacting member 166 (such as, for
 example, a bolt head, a small angle iron, a fold of metal stripping or
 simply a portion of the surface of the arm 164) that contacts the release
 pin 124 when then arm 164 pivots counter-clockwise. The core shaft 142 of
 the solenoid 140 is attached to the handle 130 (for example, via a slide
 or a pin in a lengthwise-extending cut-out portion of the handle) so that
 when the solenoid coil is energized (in the illustrated embodiment, the
 core is then pulled inward, to the left), the handle is forced to pivot
 counter-clockwise.
 In embodiments of the invention in which the handle 130 and solenoid core
 142 are connected, as in FIG. 1, the solenoid 140 is preferably chosen
 such that the core is able to move freely in and out when the solenoid is
 not energized. This allows for both automatic and manual retraction of the
 tongue jack arrangement using only the single, shared flexible control rod
 150, with no need for any special mechanism for switching from the one
 retraction mode to the other. It is also possible to include two separate
 flexible control rods--one for the handle and one for the solenoid.
 Whenever the handle 130 is moved to the left (that is, is pivoted
 counter-clockwise), either by the user or by retraction of the solenoid
 core shaft, the one end (at the handle 130) of the central control rod 144
 will be pulled so that the pivoting arm 164 is pulled by the other end of
 the rod 144 towards the release pin 124. When the release pin is
 contacted, the gas cylinder 122 expands, which causes the arm 126 (and
 thus the jack arrangement 106) to pivot counter-clockwise into the
 retracted position.
 When the handle pivots back clockwise (to the position illustrated in FIG.
 1), the arm 164 will pivot away from the release pin 124 under the outward
 force of the pin. If the ends of the control rod 144 are rigidly attached
 to the handle 130 and arm 164, then the motion of the rod 144 itself will
 cause the arm 164 to pivot away.
 In order to provide for automatic retraction of the tongue jack arrangement
 106, it is necessary to be able to activate the solenoid 140 even when the
 user forgets to do so manually using the handle 130. Accordingly, the
 solenoid 140 is preferably connected to the vehicle's 102 battery 170 (or
 to some other voltage-supplied part of the vehicle's electrical system)
 via at least one switch 172, and a contact 174 that allows the trailer to
 be electrically connected to the vehicle. (Such contacts are well known
 and are used, for example, to connect the trailer's tail lights to the
 vehicle's electrical system.)
 The switch 172 should preferably be connected (preferably in parallel) to
 or be part of the electrical system of the vehicle that is activated only
 when the vehicle is moving, is about to move, or is preparing to move,
 that is, whenever the trailer is in a potentially dangerous configuration
 with the tongue jack arrangement 106 deployed and the vehicle ready to tow
 the trailer too fast. There are many such possible connections; the
 preferred connection will in general depend on the vehicle and may be
 chosen using normal design considerations. In some countries such as
 Sweden, most vehicles' head and tail lights are automatically turned on
 whenever the vehicle's engine is running. The switch 172 could, in such
 case, be connected to the headlight supply circuit such that the switch
 172 closes when current is supplied to the headlights. Another alternative
 would be to connect the switch 172 to close along with the vehicle's
 ignition switch. Yet another possibility is to connect the switch in
 parallel to the rear brake lights--even in vehicles with automatic
 transmissions, the brake lights are often activated briefly when the shift
 lever is moved out of the "K" position; in most others, it is necessary
 to depress the brake pedal even to move the shift lever out of "K."
 Still another activating circuit for the switch 172 could be the switch
 that senses that the parking brake has been released.
 When the trailer 100 (that is, the solenoid 140) is connected electrically
 to the vehicle via the contact 174, and the switch 172 is closed along
 with whichever activating circuit is used, then the solenoid 140 will be
 energized, the core 142 will be pulled in, the handle 130 will be pivoted
 counter-clockwise, the arm 164 will be pivoted towards the release pin 124
 by the flexible control rod 144, the gas cylinder 122 will be free to
 expand, which will cause the arm 126 to pivot and the tongue jack
 arrangement 106 will rotate counter-clockwise into the retracted position.
 The invention thus provides that whenever the vehicle is moving, is about
 to move, or is preparing to move, the solenoid 140 will be energized and
 the energy stored in the device 122 (such as the cylinder) is released and
 used to retract the tongue jack arrangement 106.
 A switch 176, such as a standard microswitch, is preferably provided, for
 example, in series between the contact 174 and the solenoid 140. The
 switch 176 is mounted on the tongue or at some other convenient position
 so that, when the tongue jack arrangement 106 is in the mainly horizontal,
 fully retracted position, it physically contacts and opens the switch 176,
 thus de-energizing the solenoid 140. This will then free the arm 164 to
 pivot away from the release pin 124 and "lock" the gas cylinder 122, and
 thus the tongue jack arrangement 106 itself. The tongue jack arrangement
 106 thus is held securely in the retracted position until the user
 manually frees the cylinder 122 (via the handle 130) and moves the tongue
 jack arrangement back into the vertical, deployed position, which then
 re-pressurizes (compresses) the cylinder 122 for its next use.
 A gas cylinder 122 is preferred as the energy-storing device, because it is
 easy to operate, is reliable, is commercially available, and locks
 securely whenever the release pin 124 is not depressed (or pulled out,
 depending on the chosen cylinder, in which case the arm 164 must be
 remounted to pull out rather than push in the pin 124). It would also be
 possible, however, to use a spring, as long as it can develop sufficient
 force to retract the tongue jack arrangement 106 while still being easy
 enough for users to recompress, and provided that some locking mechanism
 is included to prevent accidental deployment of the tongue jack
 arrangement 106.
 In FIG. 1, the gas cylinder 122 and arms 126, 164 are shown mounted below
 the tongue 104. This is not necessary. Rather, these members (and the
 related brackets, etc.) may be mounted above the tongue, or even on its
 side, as long as modifications are made to enable the cylinder 122 to
 cause the tongue jack arrangement 106 to retract. The needed modifications
 will be obvious to skilled mechanical designers. If the gas cylinder is
 properly aligned with the solenoid and/or handle, then one could replace
 the sheathed, flexible control rod with a rigid control rod or shaft.
 It would also be possible to make the invention even more self-contained by
 including a dedicated voltage source that is independent of the vehicle's
 battery. Conventional mechanical actuators or electrical sensors could
 then be attached to the trailer or tongue to sense impending towing of the
 trailer based on trailer motion or position alone and to energize the
 solenoid or mechanically release the cylinder when sensing this. One
 could, for example, sense the speed of rotation of the trailer's wheel, or
 of the jack wheel 110, and activate the solenoid if this speed indicates
 movement faster than what a user could cause simply by pulling the trailer
 by hand. The disadvantages of such a solution, however, include the need
 for the independent battery (unless purely mechanical actuation is
 provided) and the need for additional sensors.
 Recall that FIG. 1, in order to make the invention more clearly
 understandable, is not necessarily to scale; indeed, the entire
 arrangement according to the invention will in general be much smaller,
 relative to the vehicle and trailer, than appears in FIG. 1. It is
 therefore also possible to manufacture all or at least most of the various
 components of the invention as a unit that can be quickly and conveniently
 mounted on or retrofitted onto existing tongue jacks.