GB2223182A

GB2223182A - Concrete mixer

Info

Publication number: GB2223182A
Application number: GB8922195A
Authority: GB
Inventors: Alastair Mearns Milne
Original assignee: DOUBLE M IND Ltd
Current assignee: DOUBLE M IND Ltd
Priority date: 1988-10-03
Filing date: 1989-10-03
Publication date: 1990-04-04
Also published as: GB8922195D0; GB8823136D0

Abstract

A mixer has a drum (22) bearing a ring gear (26) which is engaged by a drivable gear wheel (32). The ring gear (26) is shielded by an annular guard (52) having a paraxial wall (54) and an inward flange (58). It may be formed in two semicircular portions (52a, 52b), securable together by bolts (55) passed through circumferentially extending plates (53). There may also be a guard (64) for the drivable gear (32) on the side remote from the ring gear (26). A motor (34) is desirably provided with a water-resistant casing (36). <IMAGE>

Description

CONCRETE MIXER The present invention relates to a concrete mixer.

Thus the invention provides a concrete mixer comprising a mixing drum having an axis of rotation; a yoke in which the drum is supported so as to be rotatable about said axis; a stand in which the yoke is mounted pivotably whereby the axis of the drum is tiltable; and drive means for rotating the drum about its axis, said drive means including a driveable gear wheel mounted adjacent the drum; said drum having means defining an external circumferential ring gear coupled to said driveable gear wheel; the concrete mixer further including gear guard means comprising an annular guard mounted coaxially with said drum so as to surround the circumferential ring gear and impede access to it.

The annular guard may comprise an axially extending portion and a radially inwardly projecting flange. The guard means may include a further guard shielding the driveable gear wheel on the side remote from the ring gear.

The annular guard may be formed of two sections each extending part of the way around the circumference with means for connecting them to form an annulus. Desirably there is a motor for rotating the drum housed in a waterresistant housing. (The utility of this is not restricted to mixers having annular guards as specified above).

An embodiment of the invention will now be described in greater detail with reference to the accompanying drawings in which: Fig.l is a schematic exploded view, partly sectional, of a concrete mixer embodying the invention; Fig.2 is an axial section of the annular guard; and Fig.3 is a plan view on a larger scale of a portion of the guard shown in Fig.2.

The illustrated concrete mixer has a stand 10 that has two ground engaging wheels 12 at one end, and a ground engaging leg 14 at the other. A pair of upright arms 16 pivotably support a yoke or bow 18 (via collars 19). The bow 18 is a U-shaped tube which, at its lowest point, bears an upwardly-extending drum bearing shaft 20. A cup-shaped bottom drum portion 22 is rotatably mounted thereon. The mouth of the drum portion 22 has a radially outward flange 24 whose undersurface is formed as a ring gear 26. One of the arms 28 of the bow 18 is, adjacent its top, penetrated by a drive shaft 30 bearing at its inner end a driveable gear wheel 32 which engages the ring gear 26 from beneath.

A drive motor 34 is enclosed within a motor guard case 36 which is mounted to the stand 10 via a collar 38. The case is formed of two case parts 36a, 36b each having the form of a rectangular tray lacking one side wall. The mouths of the trays nest together, the marginal regions of one being received in the other, so that an approximately cuboid box, open below owing to the absent walls, is formed. The nesting arrangement gives a substantially watertight enclosure. The trays 36a, 36b have lower apertures 37a which are located in register, so that the trays can be connected by bolts about which they can hinge so as to open above. At the top they have flanges 37b by which they are releasably clampable. The motor 34 is carried by a mounting plate 35 which fits snugly within the enclosure formed by the trays 36a, b to complete the case.It is located by means of bolts passed through slots 36c in the trays. It may have drainage openings. The case 36 also contains a drive pulley 40 which is journalled on the drive shaft 30 and coupled to the motor 34 via a belt (not shown). Thus the drum is rotatable about the axis of the drum bearing shaft 20 by the motor 34. To adjust the belt tension, the flanges 37b are released and the case halves 36a, b are pivoted apart. It is then possible to push the motor up or down, to an extent determined by the length of the slots 36c. The drum is tiltable with the bow 18 relative to the stand 10. To facilitate this, the pivot shaft 42 opposite to the drive shaft bears a tilt wheel 44.

The drum also includes an upper drum portion 46, having a flange 48 for securing to the flange 24 of the lower portion; and mixing blades 50 secured to both drum portions.

The mixer also has simple and robust guard means. It has already been mentioned that the motor 34 and drive pulley 40 are completely enclosed within a case 36, so that no moving parts are accessible. Additionally we provide an annular guard 52 for the ring gear 26. This has a paraxial wall 54 interrupted by a pair of cut-outs 56; and an inward flange 58. The guard 52 is slid over the drum (mounted on the bow 18 and stand 10), and the cut-outs 56 receive inwardly-projecting portions 60 at the tops of the arms of the bow 18. These portions 60 bear downwardly-extending flanges 62. These serve as mounting plates, and have apertures through which fixing bolts for the guard 52 are passed. When thus mounted, the guard 52 is closely spaced from the ring gear 26, and shields it from above and from the outside. For still greater safety we may provide a guard 64 for the driveable gear wheel 32. This may be an L-section plate mounted to the adjacent mounting plates 62 so as to shield the driveable wheel 32 from below and from the outside. The guard 64 may be curved so as to extend around a part of the circumference of the drum on each side of the driveable gear. For example it may extend over 45".

A like guard may be provided at the other side, fixed to the other mounting plate 62.

For easier mounting of the annular guard 52 it may be in two like parts 52a, 52b. These are placed with their ends in abutment and secured by plates 53 which extend circumferentially and are engaged by nuts and bolts 55.

Claims

1. A concrete mixer comprising a mixing drum having an axis of rotation; a yoke in which the drum is supported so as to be rotatable about said axis; a stand in which the yoke is mounted pivotably whereby the axis of the drum is tiltable; and drive means for rotating the drum about its axis, said drive means including a driveable gear wheel mounted adjacent the drum; said drum having means defining an external circumferential ring gear coupled to said driveable gear wheel; the concrete mixer further including gear guard means comprising an annular guard mounted coaxially with said drum so as to surround the circumferential ring gear and impede access to it.

2. A concrete mixer according to claim 1 wherein the annular guard comprises an axially extending portion and a radially inwardly projecting flange.

3. A concrete mixer according to claim 1 or claim 2 wherein the annular guard is formed of two sections each extending part of the way around the circumference, with means for connecting them to form an annulus.

4. A concrete mixer according to any preceding claim wherein the guard means includes a further guard shielding the driveable gear wheel on the side remote from the ring gear.

5. A concrete mixer according to any preceding claim having a motor for driving the gear wheel, said motor being housed in a water-resistant housing.

6. A concrete mixer according to claim 5 wherein the motor housing comprises two tray portions that engage together, with a marginal region of one tray portion nesting within a corresponding marginal region of the other tray portion.

7. A concrete mixer substantially as herein described with reference to and as illustrated in the accompanying drawings