Cover

Abstract

 Concrete mixer vehicles (100) having a recessed man-access way (114) in mixer drums are known. Preferably such man-access ways (114) have a closure (118) within the profile of the drum (102). A continuing problem in that the closure (118) may still be a safety hazard as the drum (102) rotates.
A cover (124) for such a man-access way (114) is disclosed. The cover (124) may be made of a plastics, a composite or a metal. It may have engagement means (142,144;128) cooperating with corresponding portions on the man-access way or may be secured by the inherent resilience of the material. A handle (126) may be provided and may be removable.

Description

[0001] This invention relates to a cover for a man-access way in a concrete mixer drum.

[0002] The drum of an inclined axis concrete mixing vessel is normally made of a number of cylindrical and/or conical sections joined to one another so that they share a common axis. One end of the drum is closed with a permanently attached disc and the other end of the drum is permanently open. The drum conventionally has a number of blades or fins attached to the inside surface of the drum so as to form one or more helices which run the length of the drum.

[0003] The drum is used to agitate and mix components of a concrete mixture, which are abrasive and can wear the blades and drum. Therefore it is desirable to be able to perform periodic inspections of the interior of the drum to ensure that it is serviceable and does not need repair. Furthermore, over the course of time there may be a build up of concrete aggregate within the drum and on the blades or fins. It is desirable to be able to remove this build up to reduce the accumulated weight of the drum and also to optimise performance of the mixer.

[0004] It is known to provide a man-access way allowing a worker access into the drum without having to climb into the drum from the permanently open end. The latter is generally regarded as unsafe since the worker has no easy route out of the drum.

[0005] A further safety issue in the operation of concrete mixers is that in use the drum is rotating. Consequently if there are any protrusions from the surface of the drum these protrusions could catch objects or workmen as the drum rotates causing damage to the workmen or objects.

[0006] In order to overcome these two problems in GB 2 392 113 an easily operable man way cover is provided in which the cover and cover retention means are all arranged such that substantially all the retention means are within the profile of the drum.

[0007] According to a first aspect of the invention there is provided a concrete mixer drum comprising a man-access way the man-access way having a closure characterised in that the drum further comprises a cover adapted to extend over the man-access way and retention means adapted to secure the cover to the drum.

[0008] Such an arrangement conveniently allows a cover to be applied over a recessed man-access way such that an edge of the recess or a part of the man-access way cover may not catch on objects or workmen as the drum rotates. In particular latch mechanisms of the closure are often complex and could catch on clothing. The cover prevents this occurring.

[0009] Preferably the man access way is recessed within a profile of the drum.

[0010] Preferably the cover is arcuate.

[0011] Preferably the arcuate cover conforms to the curvature of the profile of the drum.

[0012] In a desired embodiment the cover further comprises a dependent flange.

[0013] Conveniently the retention means may comprise biased catches adapted to engage on co-operating portions in a recessed man access way.

[0014] Alternatively the retention means may comprise a bayonet type engagement with corresponding lugs or sockets in the recessed man-access way.

[0015] Preferably some form of handle is provided to facilitate positioning of the cover over the recessed man-access way or its removal from the man-access way.

[0016] Advantageously the handle may be within the profile of the drum.

[0017] Preferably the cover is formed out of a plastics material, preferably moulded. Alternatively it may be made of composite materials, or may be made of metal.

[0018] When the cover is formed of a moulded plastic it may be formed such that it has to be deformed to fit within the recessed man-access way. Once in position it is secured by the inherent resilience of the material acting to press a depending flange against the perimeter of the man-access way. Other forms of engaging portions could be utilised.

[0019] According to a second aspect of the invention there is provided a cover for a man-access way in a concrete mixer drum characterised in that the cover is arranged and adapted to extend over the man-access way and retention means secure the cover to the drum.

[0020] Any features, structural or otherwise, discussed in relation to the first aspect of the invention are equally applicable to the second aspect of the invention.

[0021] According to a third aspect of the invention a method of improving the safety of a concrete mixer comprising a drum having a recessed man-According to a third aspect of the invention a method of improving the safety of a concrete mixer comprising a drum having a recessed man-access way opening and a closure, comprises securing a cover in the opening the cover arranged to extend over the man-access way and retention means securing the cover to the drum.

[0022] According to a fourth aspect of the invention there is provided a cover for a recessed man-access way in a concrete mixer drum comprising a shield adapted to extend over a man-access way in use and retention means adapted to secure the cover to the drum.

[0023] According to a fifth aspect of the invention there is provided a concrete mixer drum including a recessed man-access way in combination with a cover for the man-access way the cover comprising a shield extending over the man-access way and retention means to secure the cover to the drum.

[0024] According to a sixth aspect of the invention a method of improving the safety of a concrete mixer having a recessed man-access way opening comprises securing a cover in the opening, the cover comprising a shield extending over the man-access way and retention means adapted to secure the cover to the drum.

[0025] An embodiment of the invention will now be discussed, by way of example only and with reference to the accompanying drawings of which

Figure 1

shows a diagrammatic view of a concrete mixer.

Figure 2

shows a plan view of a cover for a recessed man-access way in accordance with an aspect of the invention.

[0026] A concrete mixer truck 100 is shown in Figure 1. The truck 100 comprises a mixer drum 102 mounted on a bed 104. The drum 102 comprises a hollow barrel-shaped body 106 the walls of which taper towards both a closed end 108 and an open end 110 at the opposite end of the drum from the open end. The closed end 108 is closed with a circular end plate 109 welded to the body 106. The body 106 is mounted such that a central axis of the body is at an angle to the truck bed 104 so that the closed end 108 is lower than the open end with the closed end 108 being adjacent a cab 111 of the truck 100. At the closed end 108 of the drum 102 there is a recessed man-access way 114 comprising a recessed hole 116 and a closure plate 118 arranged to cover the hole 116 and releasably affixed to the drum 102 by latching means generally indicated at 120.

[0027] The closure plate 118 is arranged to be removed to allow a workman access to the interior of the body 106 through the hole 116. Access to the interior of the body 106 is desirable to facilitate inspection, maintenance and repair, etc.

[0028] As can be seen in more detail in Figure 2 a recessed man-access way cover 122 comprises in this embodiment an arcuate shield 124 provided with a centrally located handle 126 and a depending flange 128 extending around the rim 130 of the shield 124.

[0029] As can be seen in Figure 3 the arcuate shield 124 is curved so as to match the curve of a profile of the drum 102. In this embodiment the handle 126 is of the kind that has a curved grip 132 flexibly fixed to a mounting 134 in a recess 136 at the centre of the shield. The grip 132 may be releasably engaged by a clip allowing the handle to be held within the recess 136. In other embodiments the shield may simply be provided as a planar member.

[0030] It will be understood that other forms of handle may be used in conjunction with the shield 124. For example the shield 124 may be provided with a number of depressions allowing the shield 124 to be manipulated by a workman.

[0031] Turning to Figure 3 it can be seen that the man-access way hole is defined by an inwardly directed shoulder 140 around the perimeter of the hole. The shoulder 140 is provided with lugs 142 with which clips 144 on the depending flange 128 engage.

[0032] A variety of forms of clip or other retention means can be envisaged. For example, an alternative form of clip may be the kind of clip used to hold a decorative wheel trim onto a vehicle wheel. Another alternative may be to use a bayonet style engagement with lugs 142 in which appropriately shaped recesses or openings are provided on or in the flange 128.

[0033] Another alternative is to form the shield 124 and flange 128 from moulded plastic. The dimensions of the shield and flange can be such that the cover 122 may be push fitted into the man-access way hole. Being formed of moulded plastic allows the shield to deform slightly on the flange is pushed into the hole. Forces arising from the deformation of the shield act to force the flange against the perimeter of the hole thus securing the cover in the hole.

Claims

1. A concrete mixer drum comprising a man-access way, the man-access way having a closure characterised in that the drum further comprises a cover adapted to extend over the man-access way and retention means adapted to secure the cover to the drum.

2. A concrete mixer drum according to claim 1 in which the man-access way is recessed within a profile of the drum and the cover is arcuate and conforms to a curvature of the profile of the drum.

3. A concrete mixer drum according to claim 1 or claim 2 in which the cover further comprises a dependant flange.

4. A concrete mixer drum according to claim 1 in which the retention means comprise biased catches arranged to engage with co-operating portions on the man-access way or bayonet type engagement means arranged to engage with corresponding lugs or sockets on the man-access way.

5. A concrete mixer drum according to claim 1 in which the cover is resiliently deformable and is secured in place by means of the resilience of the material acting on an engaging portion.

6. A concrete mixer drum according to any preceding claim in which the cover is made of one of a moulded plastics material, a composite material, or a metal.

7. A concrete mixer drum according to any preceding claim in which the cover is provided with a handle and the handle is preferably provided within the profile of the drum.

8. A cover for a recessed man-access way in a concrete mixer drum characterised in that the cover is arranged and adapted to extend over the man-access way and retention means secure the cover to the drum.

9. A cover according to claim 8 in which the cover is arcuate and preferably conforms to a curvature of a profile of the drum.

10. A cover according to claim 8 or 9 in which the retention means comprises one of spring biased catches arranged to engage with co-operating portions on the man-access way, or bayonet type engagement means arranged to engage with corresponding lugs or sockets in the man-access way.

11. A cover according to claim 8 or 9 in which the cover is resiliently deformable and is secured in place by means of the resilience of the material acting on an engaging portion.

12. A cover according to anyone of claims 8 or 11 in which the cover is made from one of a moulded plastics material, a composite material or a metal.

13. A method of improving the safety of a concrete mixer comprising a drum having a recessed man-access way opening and a closure characterised in that a cover is secured in the opening, the cover extending over the man-access way and retention means securing the cover to the drum.

Drawing