Self-winding cable reel

A self-winding cable reel having a base plate which receives the cable drum on a bearing spindle. The technical problem is a stable and concentrated construction of all the functional parts on a base plate and a contact arrangement comprising a small number of individual parts. A circumferential stub (39) of the cable drum (3) projects into a U-shaped channel of the base plate (1), said channel being formed by a second circumferential wall (19), a second annular wall (20) and a third circumferential wall (21), a chamber (6) of the base plate (1) adjoins a window (26) of the third circumferential wall (21) and receives a winding spring (8) fastened to the circumferential stub (39), the third circumferential wall (21) has at least one further window (28), through which a braking roller (11) reaches and bears against the inner surface of the circumferential stub (39), a central annular wall (22) of the base plate (1) receives contact rings (12, 13) and carries the bearing-spindle (2), and an annular wall (40) of the cable drum (3) carries sliding contacts (14, 15).

BACKGROUND OF THE INVENTION
 1. FIELD OF THE INVENTION
 The invention relates to a self-winding cable reel having a base plate
 which receives the cable drum on a bearing spindle.
 2. DESCRIPTION OF THE PRIOR ART
 A cable reel of this type is known from DE 40 25 409 C1. Here, the cable
 drum is of multipart design and the arrangement of the functional parts,
 such as winding spring, brake and slip rings, is complex.
 SUMMARY OF THE INVENTION
 The object of the invention is a stable and concentrated construction of
 all the functional parts on a base plate and a contact arrangement
 comprising a small number of individual parts.
 This object is achieved in accordance with the invention in that a
 circumferential stub of the cable drum projects into a U-shaped channel of
 the base plate, said channel being formed by a second circumferential
 wall, a second annular wall and a third circumferential wall, in that a
 chamber of the base plate adjoins a window of the third circumferential
 wall and receives a winding spring fastened to the circumferential stub,
 in that the third circumferential wall has at least one further window,
 through which a braking roller reaches and bears against the inner surface
 of the circumferential stub, in that a central annular wall of the base
 plate receives contact rings and carries the bearing spindle and in that
 an annular wall of the cable drum carries sliding contacts.
 The invention differs from the prior art in that all the functional parts
 are received by the base plate, the braking forces of the braking roller
 and the tensile forces of the winding spring being transmitted inside the
 base plate to a circumferential stub of the cable drum, so that only low
 moments of force occur in the operation of the cable reel. The arrangement
 of the contact rings with integrally formed plug pins or flat plugs on the
 base plate has the advantage that the contact rings can be easily
 exchanged if another type of connection is required, for example flat
 plugs of different thickness or made of different material.
 Secure reception and retention of the winding spring is obtained in that
 the winding spring is fastened to a central spindle of the chamber.
 Uniform loading of the slip rings is obtained in that the two sliding
 contacts are of the same design and in that the contact heads of the
 sliding contacts are approximately diametrically opposite each other.
 A stable design of the brake and easy accessibility are achieved in that a
 radial guide for a braking lever is provided on the side of the base plate
 opposite the bearing spindle and in that the braking lever has slots
 oriented symmetrically with respect to the guide for the purpose of
 guiding a spindle of a braking roller. The brake can be mounted from the
 free side of the base plate and exchanged at any time. A quick exchange of
 a defective brake is thus possible.
 Easy installation and dismounting of the brake facilitates the exchange
 thereof in that the braking lever can be pushed into the guide and the
 base plate in the axial direction and locked by guide fins and catch lugs.
 The prestressing of the braking lever into the braking position is ensured
 in that a compression spring active in the radial direction is supported
 between the braking lever and a radially oriented stud of the base plate.
 Firm holding and travel limitation for the centrifugal weights is achieved
 in that centrifugal weights guided in radial guides of a flange of the
 cable drum engage, with slots, over catch elements of the guides.
 Simple and reliable strain relief is achieved in that clamping strain
 relief elements are provided inside the core of the cable drum.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The cable reel comprises the following main parts: a base plate 1 with a
 hollow bearing spindle 2, a cable drum 3 with a hub 4 seated on the
 bearing spindle 2, a bush shaped closure 5 with catch hook 57 for the
 purpose of retaining the cable drum 3 or its hub 4 on the bearing spindle
 2, a roller 7 with a winding spring 8, said roller being received in a
 chamber 6 of the base plate 1, a braking lever 9 with a compression spring
 10 and a braking roller 11, said braking lever being received in a radial
 guide 27 of the base plate 2, 1 as well as electrical functional parts
 such as two contact rings 12, 13 and two resilient sliding contacts 14,
 15. The chamber 6 and the guide 27 are open on the side of the base plate
 1 opposite the bearing spindle 2. Centrifugal weights 16 are guided and
 held in a flange 36 of the cable drum 3.
 These main parts of the cable reel are explained in detail hereinbelow.
 The base plate 1 is the load-bearing component of the cable reel and is
 installed in a housing (not shown) and locked or held in some other way
 therein. The base plate 1 comprises an outer, envelope-shaped first
 circumferential wall 17, a first annular wall 18 oriented in a radial
 plane, a further, envelope-shaped second circumferential wall 19, the two
 circumferential walls 17, 19 each adjoining the first annular wall 18 in
 opposite directions, a second annular wall 20 oriented in a radial plane,
 an inner, envelope-shaped third circumferential wall 21, which forms a
 U-shaped channel with the second annular wall 20 and the second
 circumferential wall 19, a third radial annular wall 22 and the central
 bearing spindle 2 for the hub 4 of the cable drum 3.
 Situated on the side of the base plate 1 opposite the bearing spindle 2, in
 the region of the first annular wall 18, is the circular chamber 6, in the
 center of which is formed a hollow spindle 24 with catch lugs 25 at its
 end face. The wall of the chamber 6 contacts the second circumferential
 wall 19. In the contact region, a window 26 is formed in the second
 circumferential wall 19 and the wall of the chamber 6.
 Also situated on said side of the base plate 1, in the region of the first
 and second annular wall 18 and 20, is a radially oriented, profiled guide
 27 for the braking lever 9, which engages, with guide fins 50, catch lugs
 51 and pins 52, in slots 29 or undercuts and cutouts of the guide 27. Only
 one each of the guide fins 50 and catch lugs 51 can be seen, on one side
 of the braking lever 9. Formed on both sides of the guide 27, in the inner
 third circumferential wall 21, are windows 28 for the braking roller 11,
 of which one window 28 for one winding direction of the cable can be seen
 in FIG. 2. The other of these windows 28 is situated in the
 circumferential direction symmetrically with respect to the slot 29 of the
 guide 27. An approximately radially oriented wall 30 adjoins each end,
 facing the guide 27, of each window 28. A radial stud 31, aligned with the
 guide 27, for the purpose of receiving the compression spring 10 is
 integrally formed on an extension 32 of the bearing bush 2. The braking
 lever 9 is inserted into the guide 27 in the axial direction and locked
 therein by the guide fins 50 and catch lug 51 and secured and prestressed
 into the braking position by the compression spring 10. The braking lever
 is dismountable in the axial direction. It can thus be exchanged at any
 time if it has been damaged.
 The two contact rings 12 and 13 are let into the third annular wall 22,
 said contact rings each carrying a plug pin or flat plug 33 and retaining
 tabs 34 which are inserted through passages of the third annular wall 22
 and firmly hold the contact rings 12 and 13 and enable the electrical
 connection thereof. Contact rings 12, 13 made of different materials and
 of different dimensions, especially thickness dimensions, may be installed
 in a same base plate 1. A push-on sleeve of a connecting line (not shown)
 can be directly pushed onto the plug pins or flat plugs 33.
 Two flanges 36, 37 are seated on a spool core 35 of the cable drum 3. Two
 pocket-shaped guides 38 for centrifugal weights 16 are formed in the
 flange 36. Catch elements 53 of each guide 38 engage in slots 54 of each
 centrifugal weight 16, thus allowing the centrifugal weights 16 to move
 only over the braking distance preset by the slots 54.
 Adjoining the spool core 35 is a circumferential stub 39, to which on the
 one hand there is attached the winding spring 8, which is laid around the
 circumferential stub 39 when the cable is being drawn out, and the inner
 surface of which on the other hand serves as a braking surface for the
 braking roller 11.
 Inside the spool core 35, a radially oriented annular wall 40 carries the
 hub 4, which fits onto the bearing spindle 2. The strain relief device is
 also attached to the annular wall 40, as can be seen from the view of FIG.
 5. Two passages 42 for opposite winding directions of a connecting cable
 43 are provided in the spool core 35. The connecting cable 43 is clamped
 and held in position by retaining bars 44, clamping jaws 45 and lugs 46.
 The conductor ends 47 have push-on sleeves 48 which are pushed onto the
 plug pins or flat plugs 49 of the sliding contacts 14, 15. The sliding
 contacts 14, 15 are held in the annular wall 40 and bear, with contact
 heads 55, under prestress against the contact rings 12, 13. The sliding
 contacts 14, 15 are of the same design. The contact heads 55 are
 approximately diametrically opposite each other, thus resulting in a
 uniform contact pressure on the contact rings 12, 13. After these parts
 have been assembled, the closure 5 is pushed into the hollow bearing
 spindle 2 and locked by the catch hooks 57.
 The braking lever 9 engages, with the guide fins 50, guide tabs 51 and
 guide pins 52, in slots 29 and other guides of the base plate 1. As a
 result, the braking lever 9 is guided in the radial direction. The
 compression spring 10 is supported on the stud 31 of the base plate 1 and
 on the braking lever 9 and prestresses the braking lever 9 into the
 braking position. In each slot 56 of the braking lever 9 there is guided a
 spindle 58 of the braking roller 11. The slots 56 are inclined relative to
 each other and relative to the walls 30. Although it is possible to draw
 out the connecting cable in the braking position, the cable drum 3 is
 braked by the braking roller 11 and the winding spring 8 is thus inactive.
 By actuating the braking lever 9 counter to the spring tension, the brake
 is released and the winding spring 8 can thus become active.