GB2257355A

GB2257355A - Central spider for tripods

Info

Publication number: GB2257355A
Application number: GB9214581A
Authority: GB
Inventors: Jurgen Nussbaum; Leonhard Jaumann
Original assignee: Sachtler AG
Current assignee: Sachtler AG
Priority date: 1991-07-10
Filing date: 1992-07-09
Publication date: 1993-01-13
Anticipated expiration: 2012-07-09
Also published as: FR2679005B3; ITRM920153U1; IT227290Y1; FR2679005A3; ITRM920153V0; JPH0620995U; JP2582426Y2; DE9108498U1; GB2257355B; GB9214581D0

Abstract

Central spider for tripods, for fixing the spread of the tripod legs (2) even on uneven ground, with three spider arms (6) which are each articulated at their outer ends with one tripod leg and are brought together at their inner ends and held there hinge-mounted in a seat (5). Stops are provided on the seat for the spider arms which influence their spread and hold the three spider arms in different spread positions but with each having the same angle of spread. <IMAGE>

Description

Central Spider for Tripods With tripods which,for example,serve for holding film or television cameras, so-called central spiders are used for fixing the spread of the tripod legs, particularly on uneven ground. These are made up of three spider arms, which are each fixed with their outer ends on the inner side of a tripod leg and with their inner ends brought together in the vertical axis of the tripod. In order to be able to collapse the tripod, together with the central spider, the outer ends of the spider arms are hinged to the tripod legs and the inner spider arms to a common holding block, as a rule turning around a horizontal axis.

In order to be able to adjust different spreads of the tripod legs with central spiders of this type, two designs are known in principle: ith the first design, when the tripod legs are spread the spider arms lie on one plane and can be adjusted and fixed as to their length for the adjustment of spread, e.g. they are designed as telescopic arms. In order to improved the rigidity of this central spider design, the inner ends of the spider arms are often also fixed in position, eg. by means of a locking plate.

Witch the second design, the inner ends of the spider arms are hinged to a clamping ring, which can be pushed along a central column of the tripod and can be fixed to the central column, e.g. by means of adjusting screws, at different heights. With this design the spread of the tripod legs is consequently determined primarily by the variable angle at the point of the pyramid or frustum 0 of the pyramid formed by the three spider arms and thereby by variable angles between spider arms and tripod legs or between spider arms and central column. ALso as with the first design the spider arms can be adjusted as to length.

When the spread of the tripod legs is to be changed, then with the first design all three spider arms require tedious readjustment. With the second design however only the clamping ring needs to be adjusted into a new position on the central column, this of course presupposing an expensive tripod with central column.

The invention is based on the objective of producing a new design for a central spider which facilitates a quick and easy fixing of the spread of the tripod legs even with simple tripods.

This objective is achieved according to the invention by the features specified in the characterizing section of Claim 1.

According to this, on the holding block at which the inner ends of the spider arms are brought together and hinged, stops or supports are provided for the spider arms, which hold the spider arms together in different angular positions. The design principle consequently resembles the second design mentioned above, with which also the adjustment of spread of the tripod legs takes place by means of variable angles at the pyramid formed by the spider arms, but without of course there being any need, according to the invention, for a tripod with central column.

Several designs are possible for the development of holding block and stops on the "point of the pyramid", such as for example stops of variable length which can be hinged and fixed to the holding block - these to lie against the individual spider arms - rotary type switches with appropriate stops of variable length or even - for continuous adjustment of the pyramid angle rotary type sitches with continuous cams etc.

A turning handle is a robust construction, adequate for the purpose, which can be rotated around the vertical axis of the pyramid formed by the spider arms and surrounds the holding block and which has several notches on the underside of its circular side-wall, which - each in groups of three for the three spider arms - are arranged at several, e.g. four, different heights, the spider arms being able to drop into the notches. The turning handle is preferably pan-shaped and encloses the holding block, the notches being located on the edge pointing downwards and a handle being provided on the upper side of the turning handle for turning it. The swivel axis of the spider arms with this design lies within the turning handle in the holding block.

The spider arms of the central spider can have a fixed or variable length, e.g. can for example be telescopic arms.

The invention is described in greater detail below with the aid of a working example and reference to the drawings. These show: Fig. 1 represents in perspective a tripod with a central spider according to the invention made up of three spider arms and a central turning handle; Fig. 2 shows a partly sectional top view of a part of the central spider with spider arms extended; Fig. 3 a longitudinal section through the turning handle and one spider arm; Fig. 4 a section of the arrangement of the side-wall of the turning handle; Fig. 5 a partly sectional view of the fastening for the outer ends of the spider arms.

In Fig. 1 a tripod 1 is represented - with three hinged tripod legs 2 which can be adjusted as to length - which supports a swivel head 3 for a film or television camera. The spread tripod legs 2 are held in the spread position by means of a central spider 4, so that the tripod has a secure position.

The central spider 4 has a central seat 5 as well as three spider arms 6.

The spider arms 6 are brought together, cp. Figs. 2 and 3, with their inner ends in a hinged star 7 and are each swivel-mounted around a shaft 8 in the three arms of the hinged star. A panshaped turning handle 9, which can rotate around the star axis, is connected with the hinged star 7. The side-wall of the turning handle 9 is designed as control ring lO, which encloses the hinged star and is mounted so as to slide on the outer walls of the individual star arms. On the upper side of the turning handle a handle 11 is provided.

The spider arms 6 are telescopic arms, the length of which can be adjusted by a clamping device 12 with a handle The outer end of each spider arm 6 is designed as a fork 13 with a seating slot 14 and can be flexibly clamped'in a coupling nut 15 (cp.

Fig. 5) on a tripod leg 2.

The control ring 10 has several recesses 16 along its lower edge turned towards the spider arms 6, the arrangement of which is shown schematically in Fig. 4 along the course of a section of the control ring 10 in a view of its inner wall, the section up to the broken line corresponding to a circumferential angle of the control ring of 1200 and consequently being assigned to one spider arm 6. Four recesses 16 of varying depths a, b, c and d are provided for each spider arm, as seen at the lower edge of the control ring.

This arrangement of the recesses is repeated around the circumference, so that recesses of a certain depth are available in each case in groups of three. The spider arms can drop into these recesses 16, as shown by means of dotted lines for the recess with depth b. The recesses are graded as to their depths in such a way that when the spider arms drop into the recesses of depth a, the spider arms lie on one plane, when they drop into the recesses of depth b an angle of 300 is assumed in relation to the specified plane, when they drop into the recesses of depth c an angle of 400 is assumed and when they drop into the recesses of depth d an angle of 500 is assumed as against the specified plane.In order to obtain a good seating for the spider arms, the recesses of depths b, c and d each have top slopes 17 with a suitable incline against which the upper sides of the spider arms - in this case circular in cross-section - fit snugly.

In order to be able to easily adjust and relocate the individual stop positions for the spider arms, another ball catch 18 is provided between the turning handle 9 and the hinged star 7, which engages in the separate stop positions in the hinged star.

When the spread of the tripod legs 2 of the tripod 1 is to be changed, then the turning handle 9 is brought into the desired position, in which the ball catch 18 then engages in the hinged star 7. This can of course also take place when the tripod legs 2 are spread, the tripod legs being easily folded until they emerge from their respective recess 16 to the extent that the control ring 10 can be turned on by means of handle 11. The entire tripod 1 with built-in central spider 4 can be completely collapsed and transported. There is maximum spread when all spider arms are extended to their full length and lie on one horizontal plane.

Fig. 5 shows the hinged connection of the spider arms 6 to the tripod legs 2. The separate sections of the tripod legs 2, which can be varied as to length, are each made up, as shown in Fig.

1, of a pair of supports. The upper section with two supports 21 terminates at their lower ends in a connecting bridge 22 into which the pair of supports 23 of the adjacent lower section is guided. The connecting bridge has two flanges 24 pointing inwards, in which co-axial, spring-supported holding bolts 25 are mounted. The holding bolts 25 each comprise a bolt shaft sliding into the flanges 24, a knob 28 which lies on the outside and is supported against the flanges 24 by means of a pressure spring 29 and a bolt plate 30, the diameter of which is greater than that of the bolt shaft. When the pressure springs are released this bolt plate lies against the inner side of the flanges 24.

For inserting the spider arms 6 into the coupling nut 15 the holding bolts 25 are pushed inwards so that the ends of the spider arms formed as forks 13 with seating slots 14 can be pushed over the bolt shafts 27. Should the holding bolts 25 then be loosened, then the bolt plates 13 drop into an enlarged area 31 of the seating slot and consequently lock the spider arms.

Claims

1. Central spider for tripods, for fixing the spread of the tripod legs even on uneven ground, with three spider arms which are each articulated at their outer ends with one tripod leg and are brought together at their inner ends and held there likewise hinge-mounted in a seat, characterized in that stops (16) are provided on the seat (5) for the spider arms (6) which influence their spread and hold the three spider arms (6) in different spread positions with the spider arms each having the same angle of spread.

2. Central spider according to Claim 1, characterized in that the stops (16) are located on a common turning handle (9).

3. Central spider according to Claim 2, characterized in that the turning handle (9) has a control ring (10) which, on its lower edge facing the spider arms (6), has recesses (16) of various depths which serve as stops for the spider arms (6) and into which the spider arms (6) drop.

4. Central spider according to Claims 2 or 3, characterized in that the turning handle (9) has a handle (1] ) on its upper side turned away from the spider arms (6).

5. Central spider according to any of the preceding claims, characterized in that the seat (5) has a hinged star (7) in which the spider arms (6) are fixed and a turning handle (9) which encloses the hinged star (7) and on which the stops (16) for the spider arms (6) are provided.

6. Central spider according to any of the preceding claims, characterized in that the spider arms (6) are telescopic arms.

7. Central spider according to any of the preceding claims, characterized in that the outer ends of the spider arms (6) are fixed to the tripod legs (2) in a coupling nut (15) which is safeguarded against accidental loosening.

8. Central spider according to Claim 7, characterized in that the coupling nut (15) has two spring-supported holding-bolts (25) seated co-axially in flanges (27), which drop into a seating slot (14) of the forked ends of the spider arms (6) and lock the spider arms into position.

9. A central spider for a tripod substantially as herein particularly described with reference to the drawings.

10, A tripod fitted with a central spider in accordance with any of the preceding claims.