GB2274820A

GB2274820A - A track system for a camera dolly.

Info

Publication number: GB2274820A
Application number: GB9402415A
Authority: GB
Inventors: Leon Allen Bronson
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-02-09
Filing date: 1994-02-08
Publication date: 1994-08-10
Also published as: GB9402415D0

Abstract

A track system for a camera dolly comprises two tubular rails 6 supported by a support system comprising a plurality of support elements 9a provided with bases 65. The support elements 9a are height adjustable to vary the height of the rails 6 above the bases 65. Intermediate support elements 45 which are not in contact with the ground can be provided when the normal support elements 9a are spaced widely apart. These intermediate supports 45 are supported by cables or rigid members extending from adjacent support elements 9a. The rails 6, which are preferably packed with an acoustic damping material, are formed in sections which are coupled together by an expanding sleeve joiner. A camera dolly is also disclosed. <IMAGE>

Description

TRACK sYEM FOR A CAMERA DOLLY This invention relates to a track system for dollies of the type which support cameras used in film and video productions.

A dolly is well known for use in the television and movie industry as providing a wheeled mounting on which a camera is carried to permit movement of the camera during use in a smooth manner to alleviate vibration or camera wobble. Frequently the dolly is mounted on a temporary track which is laid for the purpose of permitting camera movement between two points in an accurate and smooth manner so that the subject of the camera can be trailed, possibly for many retakes, without deviation.

Whilst directors, directors of photography, cinematographers and grips are always looking for new approaches to a particular shot in a motion picture or video production, it is a fact that shots using a camera dolly and track have been based around the placement of steel or (more recently) alloy dolly tracks, on basically level and unobstructed sites and locations. Crude devices such as 'apple boxes' and wedges have been used to support the track over minor site variations. No allowance has been made for larger height variations.

Grips have had to resort to ingenuity and rely on timber supports and the like to construct makeshift bridges to span obstacles etc.

Heavy cast metal dollies running on steel ground-based tracks have to date constituted the accepted industry standard. However, restrictions in the sitting and laying of such tracks on location have imposed restraints on both the cinematographic possibilities and ultimately the productions concerned.

It is an object of this invention to provide an improved track system for a camera dolly especially suited to the outdoor environment for location work.

The invention provides, in a broad aspect, a track system including two rail elements, spaced equidistantly apart, each of which is preferably tubular in section.

The track system includes a height-adjustable support system adapted to support the rail elements and preferably secured to said rail elements. The support system includes a plurality of support elements provided with base elements. The support elements are height adjustable to vary the height of the rail elements above the base elements.

The track system may be provided with means to allow coarse and fine height adjustment of the rail elements.

The invention also provides a camera dolly for use with the track system as described above including wheel sets or bogies comprising at least two radially offset wheels, each wheel having an axis parallel to a tangent of one of the tubular rails at the point of contact with the wheel.

The wheel sets may be mounted on eccentric bearings to allow movement of the wheel set relative to the dolly frame as the dolly moves around corners.

To allow the track system to be fully supported and span longer distances, the support system may also comprise at least one suspended support positioned between consecutive support elements. The suspended supports so not contact the ground but are held in position by a tension means extending from the adjacent support elements to the at least one suspended support.

The tension means may be a single cable extending between the adjacent support elements and over a pinion on the end of the suspended support or cables which extend from each adjacent support element and attached to a connection means at one end of the suspended support.

The tension means are preferably attached to the adjacent support elements at a position proximate the rail elements and the tension means cooperating with the suspended support at its end distal to the rail elements.

The length of the suspended support may be increased to pretension the tension means.

When the tension means is pretensioned and a load is applied to the rail elements such as the weight of a dolly the film crew and equipment in proximity of the suspended support, tension in the tension means supports and prevents excessive deflection of the rail elements.

If the span between adjacent support elements is sufficiently long, the pretensioning may cause the rail elements to deflect upwardly but when the weight of the dolly is applied this deflection will be reduced or eliminated as the load is transferred to the tension means.

The tension means may also be a truss of rigid bracing elements attached to the rails and extending from the consecutive support elements. While this provides a rigid and strong structure, it is difficult to adjust for different loads applied to the rail elements.

Fig. 1 is a perspective view of portion of a dolly track according to the present invention, with a support system; Fig. 2 is an end elevation of the track portion of Fig. 1 with a dolly and the walkway; Fig. 3 is a side view of a rail connecting piece; Fig. 4 is an end elevation of the connecting piece of Fig. 3; Fig. 5 is a partially cut away top plan view of the connecting piece of Fig. 3; Fig. 6 is a top plan view of a curved track section with a partial dolly frame in place; Fig. 7 is an elevational view of a track section with a single suspended support; Fig. 8A is an elevational view of a track section with two suspended supports.

Fig. 8B is an elevational view of a track section of Fig. 8A showing the deflection of the rail elements; Fig. 9 is an elevational view of an embodiment of the pretensioning means of the suspended support.

Fig. 10 is a side elevational view of a bogie on a rail element showing the connecting sleeve in place; Fig. 11 is an elevational view of a support element; Fig. 12 is an elevational view of a tensioning means for rigid bracing; Fig. 13 is an elevational view of the distal end of a suspended support; Fig. 14 is an end view of the suspended support of Fig. 13; Fig. 15 is a perspective view of an embodiment of the present invention used on uneven terrain; Fig. 16 is a side elevational view of a truss support system; Fig. 17 is a plan view of the walkway subframe; and Fig. 18 is an end view of a second embodiment of support element.

Figs. 1 and 2 show portion of a dolly track assembly 1, which includes rail sections segments 10 and 11 and a frame 2.

The track includes a pair of rail members 6 arranged equidistant along the length thereof (Fig. 2). Each rail 6 is of tubular cross-section. preferred dimensions are : external diameter, 152.4mm; wall thickness 2.64mm; gauge, 800mm. Each rail 6 is preferably formed from structural grade aluminium.

Preferably, each rail 6 is packed with an acoustic damping material such as wool fibre filling, and preferably sealed at each end. More preferably the sealing takes place far enough inside the actual end to allow the use of an expanding sleeve joiner 26 of Figs. 3 and 4, to be described hereinafter to join the rail sections together to form the rail. The support system for the rail includes a cross beam or sleeper 20, preferably formed from box-section aluminium is adapted to support rails 6, as will be described hereinafter.

Sleeper 20 has a locating tube 21 at each end. Locating tube 21 is adapted to receive a reduced-diameter extension of a frame element 13 in order to secure the frame element 13 to the rail and sleeper arrangement. It may also be used as a hitching post for various support cables and tensioning wires.

Extending downwards from rails 6 are U-shaped brackets 7, which are adapted to be secured to sleeper 20, preferably by bolts 8 or the like.

The support system 2 includes a series of support elements 9, one of which is shown in Fig. 2. The support elements are preferably linked together to maintain structural integrity.

Each of frame elements 13 has a smaller-diameter tube or the like 11 (Figure 10) attached, preferably by welding, to the top thereof, such that frame element 13 may be attached to the rail 6/sleeper 20 arrangement by inserting the reduced-diameter tube 11 into tube 21.

Cross-braces 23 and 24 are provided to produce support element 9. Preferably, the cross-braces are welded to frame elements 13. If support element 9 is taller, more crossbracing may be added (as shown in Fig. 18).

Apertures 25 are provided in frame elements 13, for the coarse height adjustment of intermediate adjustment member 16. Each intermediate adjustment member 16 is slidable in frame element 13, and may be secured in a number of discrete positions using a pin, bolt or the like operating through apertures 25.

Below each intermediate adjustment member 16 is a threaded collar 17, which is adapted to receive a threaded column 18, which in turn is secured to a base element 19.

The threaded collar (17) threaded column (18) arrangement is intended to allow fine height adjustment by rotating the collar 17 relative to the column 18. This provides a continuous range of settings which can be used for fine adjustment of the height of the support element and as a consequence the rail 6.

Sleeper 20 may be provided with cars 37, each having an aperture for the attachment of an adjustable brace 12, which has a locking clamp 14 to lock the brace 12 at a particular length, brace 12 being formed of two relatively longitudinally moveable portions one portion slidably received within the other.

Fig. 15 shows a perspective view of an embodiment of the invention extending from a hill.

This figure also shows a walking platform 39 for grips. Such a platform is important, when the track section (10,11) is elevated, to enable the person pushing a dolly to have somewhere to stand and walk. Ground-level systems do not have this problem.

The platform 39 consists of a series of panels 40, each of which is preferably formed from a material such as plywood. This is placed on an aluminium subframe 71 as shown in Fig. 15, 2 which consists of rectangular frames of aluminium box section 7o provided with reinforcing plates 73 necessary for reinforcement when frame members are bolted together (not shown).

Each preferred panel is made of either 19mm or 2Smm thickness plywood, with a preferred width of 600mm, and dimensioned to rest on the aluminium frame with rubber padding therebetween.

On a curved section (Fig. 16) the shape of the panels 40 would be different, but the concept is identical. The aluminium frame is also made to the shape of the curve.

The support element 9A shown in Fig. 15 is an embodiment of the support element in its simplest form consisting of a sleeper 20 and height adjustable feet 65 at their lowest setting.

Preferably, all of the elements of support system 2 are fabricated from aluminium, except the threaded column 18 and collar 17, which are preferably formed from stainless steel. Base elements 19 are preferably formed of a metal plate 37 coated with a rubber substance 36.

Shown in Fig. 6 is a diagrammatic camera dolly 4. The dolly 4 has four wheel sets or bogies 5. Each wheel set 5 has three wheels 32, two on the outside and one on the inside.

Wheels 32 are carried on a wheel carrier 33, and are generally arranged such that their axis of rotation is generally parallel to a tangent of the tubular rail at a point where the wheel contacts rail 6 with which the dolly 4 is to be used. In this way, the two outside wheels oppose the inside wheel to prevent lateral movement of the wheels relative to the rail.

The wheel sets S are adapted to pivot on axis 34 in bearings 35,35A on dolly 4.

In order to compensate for alteration of the wheel set pivots when encountering a curved portion of track, a compensating arrangement may be provided in which bearing 35A is an offset eccentric bearing which movement of the bogies relative to the dolly frame to negotiate curve track sections.

The dolly 4 of Figs. 2 and 6 is self-steering on the rails 6 of track arrangement 1.

Figs. 3, 4 and 5 show an expanding sleeve 26 for connecting two rails 6 together, such as in 9 and 10, in Fig. 1.

The sleeve joiner 26 is a tubular portion with an external diameter slightly less than the internal diameter of a rail 6. This sleeve joiner provides both positive coupling and very accurate registration of rail sections.

The joiner 26 is split, with a longitudinal slot 38 therein. An anchor block 29 and a threaded block 28 are located respectively on either side of slot 38. Threaded bolt 27 is secured to anchor block 29 through threaded block 28 such that rotation of the bolt 27 in predetermined directions opens or closes slot 38. Buttressing 41 is attached to both 29 and 28. Thus, to secure two rails 6 together, one would insert the expanding sleeve joiner 26 into the ends of abutting rails 6, bring the rails to close abutment, and then rotate bolt 27 to expand slot 38 to clamp the joiner 26 inside both ends of rails 6.

Fig. 18 shows an augmented support system 2 for a camera dolly track; the track itself is not shown but is generally in accordance with the other Figures.

It can be seen that the ground 3 is uneven and the track assembly is arranged across a hill. In such a situation, with intermediate elements 16 being extended on at least one side, the intermediate support 16 as a whole may be slightly unsteady.

Cross-support brace 42 is intended to locate over intermediate elements 16 to brace them. Brace 42 may be constructed in much the same way as described hereinbefore with reference to support element (for example) of Fig. 2.

Use of the brace 42 enables intermediate elements 16 to still be independently extended, and the cross-brace 42 may be positioned as low as is practicable to the base of the lesser extended foot, in the case of Fig. 14, the left-hand foot.

A pin (not shown) or other securing means such as a screw, may be used to secure the cross-support brace in position relative to each intermediate adjustment member 16.

In addition, brace 42 may be secured to primary support structure 9 by the use of an adjustable brace (not shown) perhaps one of the type shown as 12 in Fig. 7.

In another aspect of the invention shown in Figs. 7, 8A and 8B, the track system may be provided with suspended supports 45,46 which do not have base elements for contact with the ground. The suspend supports 45,46 are attached to the rail 6 and supported by tension means shown as cable 47. The cable 47 may be a continuous length which extends between the adjacent support elements 9 or individual lengths which extend from support elements 9 to the suspended support 45,46 and when applicable between the suspended supports.

The cable whether continuous or individual lengths is fixed at a point 22 to the support elements in proximity to rail 6. The cable 47 extends to the ends 48,49 of the suspended support distal from the rail where the suspended support 45,46 is provided with a connection means such as a pinion 50 (see Fig. 9). In the case of individual length cables, the end of the cable may be formed into a loop 51 and the loop encompasses the pinion 50.

In the case of continuous length (not shown) cable, the pinion is used as a guide for the cable as it extends back to the other of the support elements.

As shown in Fig. 9 the suspended support 45 is preferably extendible. The pinion is located on the extendible section 52 which has a screw thread such that tuming of a wing nut 53 will extend the length of suspended support 45 and pretension the tension means since the ends of the tension means (cable 47) are firmly attached to the support elements 9.

In the embodiments shown in Fig. 8A and 8B, a single cable 47 is shown and a larger span can be accommodated by using more than one suspended support 45,46. To maintain the position of suspended supports 45,46, bracing members 54,55 may be provided to increase the stability of the suspended supports and also pretension cable 47.

The bracing members may be connected to a brace tensioner 56 (shown in Fig. 12) at one end and the suspended support 45 (shown in Fig. 13) at the other end. The suspended supports 45,46 are provided with a flange 61 for the purpose of attaching bracing members 54,55. At the tensioner 56, the bracing members are connected to wings 57 of screw threaded adjustment shaft 58 which passes through a tube 59. Tube 59 is fixed to a sleeper 20 which in turn is fixed to rail 6.

A wing nut 60 is provided to cooperate with threaded shaft 58 to raise or lower sleeper 20 relative to the suspended support thereby causing deflection in the rail 6 to counter any load. In this way, lateral restraining force can be applied to the support elements to compensate for or transmit tension to cable 47. An auxiliary cable 64 may be provided to further restrain lateral movement of the suspended supports.

The track section shown in Fig. 8B illustrates the deflection which can be caused by pretensioning the support system. When a load is applied in the proximity of the suspended supports, the track sections will resume the shape shown in Fig. 8A if the load applied is equivalent to the pretensioning of cable 47. The amount of pretensioning can therefore be determined by a simple analysis of static forces.

Fig. 14 is a side view of the suspended support end 48 shown in Fig. 13. As can be seen, the distal end of suspended support end 48 has a slot 63 which receives cable 47.

Cable 47 acts against bearing surface 68 to support suspended support 45 and a pin 62 which prevents cable 47 from easily being removed from the slot. Cable 47 is provided with a loop 69 which loops over locating tube 22. A turn buckle 67 is provided to initially tension cable 47 after installation and a rounded bearing surface 74 prevents damage to the tensioned cable.

Fig. 16 is a side view of a truss formed of rigid bracing members 66 which may be used in the invention. The bracing members 66 are fixed to the rail 6 and at each end to adjacent support elements 9. While this system is difficult to pretension, it minimizes the downward deflection of the rail when loaded.

It can be seen that the camera dolly track system of this invention is a great improvement on the prior art.

The system is capable of smoothly transporting a film or video camera, and a camera support, which could include a tripod and/or a lightweight jib arm or crane arm, together with the camera-operator, assistant and grip, over large obstacles, natural or manmade encumbrances, uneven and/or difficult terrain. It is a flexible system, providing the freedom to position the track path in many more situations than could be achieved with prior art 'ground-based' tracks.

The system is able to span & bridge walls, fences, seating, platforms, laneways, stairwells, tables, garden beds, drains, creeks, rocks, fallen trees, swimming pools, sheds, machinery and motor vehicles.

The tracks may be laid flat on the ground surface, or with only with the base elements 19 and a spacer tube (not shown) - if some vertical adjustment is required.

A range of 'height-adjustable supports' is available for those tricky situations which are invariably encountered on outside locations. Independent vertical adjustment is provided on both frame elements 13 of each support element 9.

The preferred material, structural aluminium, is much lighter to lift and carry, when compared to heavy castings and steel tracks. This system has been designed particularly with outside location work in mind.

Most of the track components of the preferred arrangement can be packed into a small 35m long trailer. This trailer can be attached to any suitable towing vehicle, then if necessary, detached on arrival at the location. Two or three lengths (9.5 metres), can even be transported on a car roof-rack.

Set-ups that would have taken hours - consuming the valuable labour time of grips crew - can now be completed in a matter of minutes. As a result, creative decisions regarding the best possible tracking-shots are no longer compromised by production budgets.

The system of this invention is relatively inexpensive to either hire, or purchase.

In addition, in less complex situations, it can be set up and operated by any member of the film or video crew, which is a big money saver on small-budget shoots where there is no allowance for a separate grips team.

The inherently structural strength of the relatively large cross-section rails 6 secured to sleepers 20 is in itself an important practical factor.

Track sections (9, 10, 11) have a preferred standing length of 3.25m, although a special 'bridging length' of 6.5m may be provided.

The preferred standard track sections have a safe load handling capacity of 550kg;

Claims

CTAIMS 1. A track system for a dolly comprising two rail elements spaced equidistantly apart along the length thereof, said rail elements being supported on a support system having at least two support elements, said at least two support elements being provided with base elements, said at least two support elements being height adjustable to vary the height of the rail elements above the base elements.
2. The track system of claim 1 wherein said at least two support elements have frame elements, each frame element receiving an intermediate adjustment element, said frame element having a course adjustment means to fix the relative position of said intermediate adjustment element over a discrete range of settings, said intermediate adjustment element being connected to said base element.
3. The track system of claim 2 wherein the intermediate adjustment element is provided with a fine adjustment means for adjustment of the position of said base element relative to said intermediate element over a continuous range of settings.
4. The track system of any one of the preceding claims wherein said support system is fixed to said rail elements and further comprises at least one suspended support, the position of said suspended support being maintained by tension means extending between adjacent support elements.
5. The track system of claim 4 wherein said tension means is pretensioned to allow a load applied downwardly to said rail elements proximate said at least one suspended support to be supported by said support system.
6. The track system of claim 5 wherein said tension means extends from the adjacent support elements at positions proximate the rail elements to a connection means at the end of said at least one suspended element distal to said rail element.
7. The track system of claim 6 wherein the length of the suspended element can be lengthened to pretension said tension means.
8. The track system of claim 7 wherein the tension means comprises a cable which extends from each adjacent support element, each cable having a loop formed at the suspended support end and the connection means is a pinion over which said loop of each cable is positioned.
9. The track system of claim 4 wherein the tension means is a single cable which extends between the adjacent support elements.
10. The track system of claim 4 wherein the tension means comprises rigid bracing element secured to said at least one suspended support and said adjacent support elements.
11. The track system of any one of claims 1,2 or 3 wherein said support system is fixed to said rail elements and comprises at least two adjacent suspended supports positioned between adjacent support elements, the position of said adjacent suspended supports being maintained by tension means extending between the adjacent support elements and between the adjacent suspended supports.
12. The track system of any one of the preceding claims wherein the rail elements comprise a plurality of individual rail sections, the rail sections being connected together by an expandable sleeve joiner.
13. The track system for a dolly comprising two rail elements spaced equidistantly apart along the length thereof, said rail elements being supported on a support system fixed to said rail elements, said support system having at least two support elements provided with base elements and at least one suspended support, the position of said at least one suspended support being maintained by tension means extending between adjacent support elements.
14. The track system of claim 13 wherein said tension means is pretensioned to allow a load applied to said rail elements proximate said at least one suspended support to be supported by said support system.
15. The track system of claim 14 wherein said tension means extends from the adjacent support elements at positions proximate the rail elements to a connection means at the end of said at least one suspended element distal to said rail element.
16. The track system of claim 15 wherein the length of the suspended element can be lengthened to pretension said tension means.
17. The track system of claim 16 wherein the tension means comprises a cable which extends from each adjacent support element, each cable having a loop formed at the suspended support end and the connection means is a protrusion over which said loop of each cable is positioned.
18 The track system of claim 17 wherein the tension means is a single cable which extends between the adjacent support elements.
19. The track system of claim 13 wherein the tension means comprises rigid bracing element secured to said at least one suspended support and said adjacent support elements.
20. The track system of claim 13 wherein the rail elements comprise a plurality of individual rail sections, the rail sections being connected together by an expandable sleeve element.
21. A dolly for use on a tubular track including a frame provided with a plurality of wheel sets, each wheel set having at least two radially offset wheels, each wheel having an axis parallel to a tangent of one of the corresponding tubular rail at the point of contact with the wheel.
22. A track system as hereinbefore described with reference to the accompanying drawings.