GB2072026A

GB2072026A - Concrete transit mixer

Info

Publication number: GB2072026A
Application number: GB8028017A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-09-13
Filing date: 1980-08-29
Publication date: 1981-09-30
Also published as: IE791742L

Abstract

A combined tank unit has an upper compartment 26 for storing a large volume of water for adding to dry concrete mix in a driven drum 11, and a lower compartment for storing a relatively smaller volume of oil for a transmission system 17 for the drive to the drum. The two compartments are separated by a common wall 25% having a good thermal conductivity and constituting a substantial part of the surface area of the oil storage compartment. This arrangement permits the oil to be cooled by the large volume of water above, dispensing with the need for a separate heat exchanger to cool the oil during use of the mixer. <IMAGE>

Description

SPECIFICATION Concrete transit mixer The present invention relates to a concrete transit mixer. In such a mixer water must be stored for adding to dry concrete mix to create a wet concrete mix, and also for cleaning out the drum. Oil must also be stored for hydrostatic transmission system for the rotary drum in which concrete is mixed. This oil must be kept below 70or. It is therefore usually necessary to provide a heat exchanger installation to keep the oil cool.

According to the present invention there is provided a concrete transit mixer comprising a combined tank unit with separate compartments for storing oil and water.

More particularly, the invention provides a concrete transit mixer comprising a mixing drum driven by a hydraulic transmission system, means for storing oil for the transmission system, and means for storing a relatively much larger volume of water for adding to dry concrete mix in the drum, wherein the oil and water storage means comprises a combined tank unit having separate compartments for storing the oil and water respectively, the two compartments being separated by at least one common wall having a good thermal conductivity and constituting a substantial part of the surface area of the oil storage compartment.

The close proximity of the large volume of cold water with the relatively small volume of oil serves as a heat exchanger for cooling the oil.

The invention also provides a dual control system for operating the concrete mixer. Preferably these are located one on each side of the mixer at the outlet end of the drum.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a concrete transit mixer according to an embodiment of the invention, Figure 2 is an enlarged side view of part of the transit mixer of Figure 1 showing the combined tank unit arrangement, and Figure 3 is a front view of the embodiment of Figure 2 without the transmission system.

In the concrete transit mixer illustrated in the accompanying drawings, concrete mix and water are rotated in a drum 11. The drum is mounted on a chassis 12 which is connected to a cab 13. The mix is put into the drum through a chute 14 and concrete leaves the drum 11 from a chute 15 at the rear of the mixer. The drum 11 is supported by struts 16 at the rear upper end of the mixer, and is rotated by a hydraulic transmission system 17, which includes a gear box 18, about a central boss 19 at its forward lower end. The transmission system is mounted on a platform 20 and fixed by a pair of mounting flanges 21 arranged one each side of the system. The flanges 21 additionally serve to support a combined tank unit for the water and oil.The tank unit, which is made of steel, is also supported by side supports 22, which rest on a lower ledge 20' of the platform 20, and beams 23 which extend across the top of the supports 22 and the mounting flanges 21 and are secured to the supports 22 with the aid of angle bars 24.

The combined tank unit comprises a first compartment 25 constituting an oil reservoir supported by the beams 23, and a second compartment 26 constituting a steel water tank of 200 gallons capacity above and supported by the oil reservoir 25, the capacity of the tank 26 being very much larger than that of the reservoir 25. The upper part of the oil reservoir 25 is formed from a folded steel plate 25' which extends into the bottom of the water tank 26 and forms a base therefor. As can be seen, the oil reservoir 25 is of relatively shaliow construction, so that the part of the steel plate 25' constituting a common wall between the reservoir 25 and the water tank 26 prevents a large area to the water in the tank 26, and represents a substantial part of the surface area of the reservoir 25.

The oil reservoir 25 is connected via a feed pipe 27 to a 1.5 gallon capacity header tank 28 whose exterior wails form part of the outer structure of the water tank 26, but which is separated from the water by sidewalls 28' and an inclined plate 29, which forms an inner wall for the water tank 26. The header tank 28 is provided with an oil filler 31 which has a threaded cap 32 and also serves as a filter and breather. The tank 28 also has an overflow (not shown) therein. The feed pipe 27 has a sight glass 33, from which the minimum required oil lever can be read, and a primary filter 34, which filters all the hydraulic oil going into the main oil reservoir 25.

There is a secondary filter (not shown) incorporated in the conventional hydrostatic transmission system.

A door 35 is provided in the front panel of the oil reservoir 25 for inspection and cleaning purposes.

The water tank 26 has disposed therein a baffle (not shown) for limiting movement of the water when the mixer is in transit. The baffle is fixed to the tank 26 by crossed vertical and horizontal baffle supports (not shown).

Water is introduced to the water tank through a water inlet aperture 36 which has a cooperating cover 37 kept in place in transit by a resilient bar 38 (see Figure 3). The water leaves the water tank 26 from an outlet 39 through a pipe (shown partially at 41) and is driven by a water pump 42 to the inside of the drum 11.

When the mixer is in use, the oil travels in a closed circuit from the reservoir 25, through a conventional main filter to the transmission system 17 entering via an inlet 43. Oil returns to the reservoir through an inlet 44. As oil passes round the hydrostatic transmission system it heats up and returns to the reservoir 25. Direct contact of the oil in the reservoir 25 and the water in the tank 26 with opposite sides of the plate 25' respectively enables heat exchange to take place acting to cool the oil to an acceptabie temperature, it being understood that the plate 25', being metal, provides a good thermal conductivity for this purpose. The large volume of water compared with the volume of oil involved enables this process to continue without the water temperature rising unduly.

It will be appreciated that the two side plates of the tank could be used for advertising.

The operation of the drum 11 is controlled by dual controls at the rear of the chassis 12, one set of which can be seen at 45 in Figure 1. The two sets are located one at each side of the chassis to ease operation of the mixer.

Claims

1. A concrefie oran -.r. rnlxer comprising a com bined tank unit with separate compartments for storing oil and water.

2. A concrete transit mixer comprising a mixing drum driven by a hydraulic transmission system, means for storing oil for the transmission system, and means for storing a relatively much larger volume of water for adding to dry concrete mix in the drum, wherein the oil and water storage means comprises a combined tank unit having separate compartments for storing the oil and water respec timely, the two compartments being separated by at least one common wall having a good thermal conductivity and constituting a substantial part of the surface area of the oil storage compartment.

3. A concrete transit mixer as claimed in Claim 2, wherein the oil storage compartment comprises a relatively shallow compartment beneath the water storage compartment.

4. A concrete transit mixer as claimed in Claim 3, further comprising an oil heater tank set into the top of the water storage compartment for maintaining the oil storage compartment full.

5. A concrete transit mixer as claimed in Claim 2, 3 or 4, wherein the combined tank unit is mounted above the transmission system attheforward end of the mixing drum.

6. A concrete transit mixer substantially as de scribed with reference to the accompanying draw ings.