GB2411381A

GB2411381A - Hinged or dismantleable structures, particularly for boat carriers

Info

Publication number: GB2411381A
Application number: GB0404513A
Authority: GB
Inventors: Paul Firby
Original assignee: DALE PRODUCT DEVELOPMENTS Ltd
Current assignee: DALE PRODUCT DEVELOPMENTS Ltd
Priority date: 2004-02-28
Filing date: 2004-02-28
Publication date: 2005-08-31
Also published as: GB0404513D0

Abstract

A boat carrier comprising a supporting spine having front and back sections hinged or releasably connected so that they can be folded together or dismantled when not in use, and two lateral arms adapted to carry respective wheels and hinged or releasably connected to the back section of the spine so that they can be folded to lie alongside the spine or dismantled when not in use. Also claimed is a supporting structure comprising hollow elongated tubular members made by rotational moulding of thermoplastics material, each member being formed at one end with a boss; and the members being connected together by a pin passing through the bosses.

Description

2411 381

HINGED OR DISMANTLEABLE STRUCTURES PARTICULARLY FOR

BOAT CARRIERS

This invention related to hinged or dismantleable structures. It arose during the design of a launching trolley for a dinghy but it is apparent that the invention could have application in other environments, for example road trailers and other frame structures, which are required to fold up when not in use but where a substantial load-carrying capability is required when unfolded and in use.

In this specification the word "boat" will be used generically to describe water born vehicle of all types and sizes including dinghies. The word "carrier" is used to describe any device suitable for supporting and transporting a boat but it is envisaged that this will normally be either a trolley such as is used for launching a boat into the water and recovering it, or a trailer designed to be pulled by a traction 1 5 device.

Launching trolleys for boats have traditionally been made of steel to provide the necessary strength and are usually galvanised to protect against corrosion in the extreme conditions in which they are used and stored. They tend to be too heavy to carry easily and too large to be transported by car or boat.

US Patent specification 4781397 (Burns) describes one attempt to design a launching trolley, which can be more easily carried. The construction described by - 2 Burns employs a steel frame attached to a back axle. The back axle can be detached from the frame; and the frame can be folded to assist transportation of the trolley when not in use. However, even when disassembled, the Burns construction cannot be shorter than the wheelspan i.e. the length of the back-axle and this factor in combination with the weight of the steel frame makes it relatively inconvenient to carry.

This invention provides a boat carrier comprising a supporting spine having front and back sections hinged or releasably connected so that they can be folded together or dismantled when not in use, and two lateral arms adapted to carry respective wheels and hinged or releasably connected to the back section of the spine so that they can be folded to lie alongside the spine or dismantled when not in use.

A preferred structure used hinge connections between the various parts specified above because it facilitates quick and easy deployment and stowing away.

However, a structure in which the parts are designed for quick release and assembly might also be practicable.

By employing the invention, it is possible to fold or dismantle the boat carrier so that it becomes very compact for carrying and storage. - 3

Preferably the front and back spine sections are hinged about a horizontal axis so that one folds on top of or under the other, whilst the lateral arms are hinged about vertical axes so that they fold against the sides of one of the spine sections, this making for a particularly compact folded arrangement.

A hinge structure which has been found to be particularly effective is formed with two opposing abutment surfaces, which serve to limit the degree of opening of the two parts so that they cannot open substantially beyond a position in which they are aligned with each other. This allows the hinge to carry the stresses imposed by the weight of the boat. All the hinges are preferably designed so that when the hinged parts are folded flat, there remains a small gap between them to avoid the risk of trapped fingers.

To give strength and stability to the hinge arrangements they are preferably constructed so that each hinged component has a boss defining a curved convex surface which engages against a correspondingly curved concave surface of a recess in the other component, the bosses being connected together by a hinge-pin. The engagement between these convex and concave surfaces helps to reduce any tendency for rotation other than about the axis of the hinge pin.

The inventor has evolved a theory that it would be possible to make each of the spine sections and the lateral arms as a single hollow rotationally moulded component including the hinge boss and recesses structures previously mentioned.

Rotational moulding of synthetic plastics material is a technique commonly used for manufacturing articles, which need to be hollow, for example tanks for liquids.

It has not however previously been considered an appropriate process to consider for use in the manufacture of structures having parts which need to be carefully engineered to fit mechanically together.

Tests conducted by the inventor prove that rotational moulding can be used to make components with sufficient detail and tolerance to form the components of a structure such as a boat trailer or trolley, that the inherently hollow nature of the rotational moulded components gives them an excellent strength/weight ratio and that the rotational moulding process can be controlled so as to give added wall thickness in selected areas where increased strength is required.

It is believed that the discovery that rotational moulding can be used effectively in this way may have useful applications for the construction of other articles and thus, according to a second aspect of this invention, there is provided a hinged or dismantleable supporting structure comprising hollow elongated tubular members made by rotational moulding of thermoplastics material, each member being formed at one end with a boss; and the members being connected together by a pin passing through the bosses.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: - 5 Fig 1 is a perspective view of a launching trolley constructed in accordance with the invention; Figs 2 shows a vertical cross-section through respective halves of a hinge joining two parts of a folding spine of the trolley of Fig 1, Fig 3 is an exploded perspective view of the hinge of Fig 2, and Fig 4 is an exploded perspective view of another hinge assembly joining the spine to two lateral arms, which carry the wheels of the trolley.

The illustrated launching trolley is made almost entirely from just six hollow rotational moulded components. The only additional components are three metal pivot pins and associated sleeves, nuts and washers, two metal axle stubs and two standard wheels. Rotational moulding uses a hollow mould formed in two separable parts which together define an inner surface conforming to the desired external surface of the finished product. In use, thermoplastics material, in powdered or particulate form, is introduced into the mould which is then turned and/or rotated in a controlled way whilst being heated to melt the plastics. In this way the inner surface of the mould becomes coated with the molten plastics. The mould it then allowed to cool, whilst still being turned, until the plastics has solidified whereupon the mould halves are separated to release the finished product. - 6

The thickness of the walls of the product can be controlled by measuring the quantity of plastics introduced. Also variations in thickness can be obtained by controlling the manner in which the turning movement takes place. This particular factor is of significance in the construction of the illustrated trailer because it allows increased strength to be given to those parts, which require the greatest strength.

Referring first to Fig 1, it will be seen that the trolley has a folding frame comprising a spine 1 formed from a front section 2 hinged to a rear section 3, and two arms 4, hinged to the rear spine section, for carrying wheels 5.

The front spine section 1 is hinged about a horizontal axis I - I to a rear section 3.

The hinge arrangement allows the two sections to be opened to the illustrated position where they are in line with each other, but no further. They can be folded together by rotating the front section 2 underneath the rear section 3 until a stop 2A engages the underside of the rear section 3. This stop 2A ensures that, there always remains a space between opposing surfaces of sections 2 and 3 so as to avoid any risk of the user trapping his fingers. The stop 2A is formed with a hole 2C in which is mounted a holding device (not shown) by which the user lifts the front end of the trolley and pulls or pushes it as required. In its simplest form the holding device could be a length of cord attached to a handle - 7 The front spine section2 is formed with two support wings 2B, which are angled upwardly away from the spine. These wings serve to locate and support the keel of the dinghy.

The rear spine section 3 is hinged to two similar arms 4 each of which has an upwardly extending projection 4A, the top extremity of which fits into a recess of a rocker 5. Opposite sides of the projection 4A are formed with small rounded bumps which make a snap-action fit into corresponding holes bored through the walls of the rocker thereby forming a pivot allowing the rocker to swivel about a horizontal axis. The recesses in the rockers are elongated to as to permit such swivelling and the rockers are thus able to conform to the angle of the hull of the dinghy. In use, these rockers 5 support most of the weight of the dinghy.

At the end of each arm 4 the plastics is deposited relatively thickly, enabling it to receive axles 4B on which the wheels rotate.

Figs 2 and 3 show in detail the hinge arrangement between the spine parts 2 and 3.

Each of these parts has a boss 6 in which a brass sleeve 7 has been set during the rotational moulding process. Fig 2 shows how this has resulted in a body of plastics surrounding and reinforcing the sleeve. Each boss has a part-cylindrical convex surface 8 centred on the axis of the sleeve 7. - 8

Axially adjacent each boss 6 is a recess 9 of a size and shape corresponding to that of the boss. The recess has a part-cylindrical concave surface 10.

When the two parts 2 and 3 are assembled together, using a suitable rustresistant nut, bolt and washer (not shown) passing through the bushes, the convex surfaces 8 of the bosses engage against the concave surfaces 10 of the recesses this giving the structure stability against bending forces in the direction of the plane of Fig 2. In addition, abutment surfaces 11, on each spine section 2 and 3, engage so as to prevent hinging movement beyond the state shown in Fig 1 where the two sections are aligned.

Fig 4 shows the hinge connections between the rear spine section 3 and the two arms 4. The principle of operation is similar to that of the hinge between spine sections 2 and 3 and corresponding parts are denoted on the drawings with identical reference numerals. Thus, on Fig 4, bosses 6 fit into corresponding recesses so that their respective convex and concave cylindrical surfaces 8 and 9 engage to give stability against turning moments other than about the hinge axes II.

To hold the arms 4 in the deployed position as shown in Figs 1 and 4 a plate 12 is bolted to the back end surface of the spine section 3. The plate 12 is able to pivot about its supporting bolt (not shown) and has slots 3A, 3B which engage behind corresponding heads of bolts (also not shown) on arms 4.

When the arms are hinged closed about vertical axes II - II they are folded neatly so that faces 4C of the arms face against faces 3A of the rear spine section. However a gap is maintained to prevent trapping of fingers by virtue of the fact that the face 3A is displaced from the axis II - II by a slightly greater distance than the displacement between axis II - II and face 4C.

The inventor has built a prototype trolley similar to that described and has proved that the principles of this invention allow the structure to be produced inexpensively with remarkably few parts all of which are highly resistant to extreme weather and water conditions. Furthermore, the folding features and the extraordinary light weight of the structure allow the trolley to be easily carried by one person in a bag or in the dinghy itself. However it will be appreciated that other structures within the scope of the accompanying claims could also give these benefits. For example, the hinges of the illustrated embodiment could be replaced by similarly designed Remountable coupling pin connections allowing quick assembly and disassembly. - 10

Claims

I A boat carrier comprising a supporting spine having front and back sections hinged or releasably connected so that they can be folded together or dismantled when not in use, and two lateral arms adapted to carry respective wheels and hinged or releasably connected to the back section of the spine so that they can be folded to lie alongside the spine or dismantled when not in use.
2 A carrier according to Claim 1 in which the front and back spine sections are hinged about an axis, which extends laterally with respect to the hinge axes of the lateral arms.
3 A carrier according to Claim 2 in which the front and back spine sections are hinged about a horizontal axis and the lateral arms are hinged about vertical axes.
4 A carrier according to any preceding Claim in which at least one of the hinges are formed by bosses at respective ends of the hinged components and a hinge-pin which passes through the bosses, each boss being associated with a corresponding recess which receives the boss of the other component, the bosses and the recesses having complementary curved surfaces extending circumferentially with respect to the hinge axis and providing support against bending forces in directions other than about the hinge axis.
A carrier according to Claim 4 in which each of the components is formed with an abutment arranged to engage the abutment of a connected component so as to limit hinge movement.
6 A carrier according to Claim 5 in which the bosses, the recesses and the abutments are defined by components moulded from synthetic plastics 1 0 material.
7 A carrier according to any preceding Claim in which a hinge between components is designed so that, when folded together, facing surfaces of components are separated by a gap sufficiently wide to prevent trapping of the user's fingers.
8 A carrier according to any preceding Claim in which the spine sections and arms are each made from a single rotationally moulded component.
9 A supporting structure comprising hollow elongated tubular members made by rotational moulding of thermoplastics material, each member being formed at one end with a boss; and the members being connected together by a pin passing through the bosses. - 12
A supporting structure according to Claim 9 in which each boss has an associated abutment arranged so that the abutments meet together to limit relative rotational movement of the members in one direction.
11 A supporting structure according to Claim 10 in which each abutment has a sleeve which bridges walls of the hollow moulded structure; and in which the pin passes through the sleeves.
12 A hinged supporting structure according to any one of Claims 9 to 11 in which each member is formed with a recess which receives the boss of the other member; the bosses and recesses having corresponding curved surfaces, which offer mutual support giving added stability to the hinged structure.
13 A hinged supporting structure according to any one of Claims 9 to 12 in which a hinge connecting two elongate members allows those members to be folded from a deployed position to a stowed position where they lie alongside each other.
14 A hinged supporting structure according to Claim 13 in which the hinge is designed so that, in the stowed position, facing surfaces of the members are separated by a gap sufficiently wide to prevent trapping of the user's fingers. - 13
A boat carrier comprising a wheeled frame constructed in accordance with any preceding Claim.
16 A boat carrier according to Claim 15 in which two of the members have upwardly extending protrusions which carry respective bearers adapted to engage the hull of the boat, the bearers being pivoted to the protrusions so as to allow them to adopt an angle corresponding to that of the hull.
17 A boat carrier according to Claim 16 in which each bearer is a hollow moulded body of synthetic plastics material formed with a recess which receives the associated protrusion, the protrusion and the bearer having detent means which connect together with a snap action to form a hinge arrangement.
18 A carrier according to any one of Claims 9 to 17 in which each of the lateral arms has an upwardly extending extension carrying a bearer adapted to engage the hull of the boat, the bearers being pivoted to the protrusions so as to allow them to adopt an angle corresponding to that of the hull.
19 A boat carrier according to Claim in which each bearer is a hollow moulded body of synthetic plastics material formed with a recess which receives the associated protrusion, the protrusion and the bearer having detent means which connect together with a snap action to form a hinge arrangement.