WO2013065060A1

WO2013065060A1 - Scmd transit mixer for production & transportation of concrete

Info

Publication number: WO2013065060A1
Application number: PCT/IN2011/000885
Authority: WO
Inventors: Amit Arun Gokhale; Anand Arun Gokhale
Original assignee: Amit Arun Gokhale; Anand Arun Gokhale
Priority date: 2011-11-03
Filing date: 2011-12-22
Publication date: 2013-05-10
Also published as: AP2014007672A0

Abstract

A stationary concrete mixing drum - SCMD transit mixer for production & transportation of the concrete is provided. The mixer has a stationary concrete mixing drum with a top open (3) and two different sets of spirals mounted on a single shaft. The larger diameter spirals are called the discharging spirals & the smaller diameter spirals are called the mixing spirals. The shaft is driven by a heavy duty planetary reduction gearbox. Further, the gearbox is driven by a mechanical drive powered by a dedicated slave engine. The shaft is provided with a unidirectional rotation. However, a bidirectional movement of the concrete is achieved by means of the spirals. Thus mixing and discharging through a controlled gate is accomplished. The mixer is provided with a set of electronic load cells (4) to actually weigh all the ingredients. The mixer is typically mounted on a normal commercial truck. The mixer is alternatively operated by a truck PTO. The mixer can be alternatively mounted on a trolley/ trailer or towed by a tractor. The cost can be reduced by 50-55%.

Description

SCMD TRANSIT MIXER FOR PRODUCTION & TRANSPORTATION OF CONCRETE

PREAMBLE TO THE DESCRIPTION :

TH E FOLLOWING COMPLETE SPECIFICATION PARTICULARLY DESCRIBES TH E INVENTION AND TH E MANNER IN WH ICH IT

IS TO BE PERFORM ED

[001.00] TECHNICAL FIELD OF INVENTION

The present invention relates to a Novel apparatus for production & Transportation of concrete. In particular, the present invention relates to production and transportation of concrete.

[002.00] BACKGROUND OF THE INVENTION

[002.01] Conventional System of Concrete Production & Transportation :

Today, Ready-mix concrete is widely used for all types of constructions and has become a necessity. It is produced by a central mixing plant called a Ready-Mix Plant installed at a particular location.

[002.02] The concrete produced by this plant is then transported to various construction sites by specially designed equipment called transit mixers. A transit mixer is a equipment having a. rotating drum which keeps the concrete mixing and alive during transport. The transit mixer drums are mounted on normal commercial truck chassis. A normal transit mixer with rotating drum is hereinafter considered as "PRIOR ART N0.1". Kindly refer to Fig. No. 1.

[002.03] A Ready-Mix Concrete plant needs a considerable amount of land and foundations. A front end loader is required to load the raw materials into the material bins of the Ready-Mix Concrete plant. A Ready-Mix Concrete plant also needs a considerable amount of power as the connected load required for its operation is very high. It also requires a dedicated source of power like a Diesel Generator set in case of power failure. Therefore the operation cost associated with the Ready-Mix Concrete plant is considerably high due to these reasons. Therefore in this system, two different equipment namely a Ready-Mix Plant, and a Transit mixer are used for the purpose of production and transportation of concrete.

[002.04] Many efforts have been made to reduce the cost of concrete production and transportation in a direction to use only the transit mixers as mean of concrete production & transportation. However such efforts have serious drawbacks and have not resulted into an acceptable replacement to the conventional system because of these serious draw backs.

[002.05] The said prior art No. 1 as mentioned in point no. 1 is the normal transit mixer used to transport concrete from the central Concrete production Plant to the place of construction. The said prior art No. 1 has many disadvantages which are discussed hereunder.

[003.00] TECHNICAL PROBLEM :

As mentioned, many efforts have been made in past to use only transit mixers as a single mean of production and transportation of concrete in order to eliminate the stationary Concrete production plant and the subsequent investment in land & foundations.

[003.01] However the biggest technical problem is faced due to the very construction & design of the transit mixer. The normal transit mixer mentioned as prior art no 1, is basically designed to transport the concrete from one place to another & to keep the concrete alive but not to produce concrete by forceful mixing like a twin shaft mixer. In long distance transport, however, the material gets mixed which is basically due to the gravitational movement implied on the material due to the drum rotation. It is further assisted by the unidirectional spirals welded on the interior of the rotating drum. The transit mixer drum is provided with continuous spirals fixed to the inner side of the drum which rotate along with the drum to either charge the material in one direction or to -discharge the material while the drum is rotating in the opposite direction.

[003.02] However many efforts were made in past to use the transit mixer to actually mix

& produce concrete by providing multiple start spirals fixed on the inner side of the rotating drum to have more homogeneous mixing after feeding materials from a dry mix batching plant. The dry mix plant is also called therefore as a Transit Mix plant. However whether dry or wet, a batching plant was still required to batch the materials on weight basis and then feed the batched material either wet or dry into the transit mixer. The combination of a transit mix plant ( or a weight based or volume based batcher) as mentioned above is hereinafter called the PRIOR ART NO. 2. Kindly refer to Fig. No. 1.

[003.03] In both the conditions mentioned in Prior Art No. 1 & Prior art No. 2. it is impossible to load a transit mixer directly with a front end loader because of two reasons : one being the very construction of the transit mixer, wherein the transit mixer cannot be provided with an opening big enough to be suitable for loading of materials by a front end loader due to its rotating drum design. Secondly the transit mixer itself cannot batch the material on weight basis. Hence a transit mixer always needs either a dry batching plant or a wet batching & mixing plant to feed itself.

[003.04] A closest solution to this problem was represented by a self loading transit mixer which is called as "PRIOR ART NO. 3". Please refer to Fig No. 3. Self loading transit mixer is a normal transit mixer having a specialized loader attachment fabricated to suit to load the raw materials into the transit mixer. The raw materials could be stocked in an open area and the transit mixer having a self loading bucket can load all the raw materials one by one into it and can produce concrete.

[003.05] However the self loading transit mixers have many disadvantages and cannot be used widely to replace the conventional system due to these limitations.

[003.06] The various problems associated with the self loading transit mixers "PRIOR ART NO.3" are as follows:

1. Due to the inability of the front end loader to load the transit mixer directly due to its very design, the self loading attachment had to be provided. The self loading attachment adds to the dead weight of the equipment and reduces the load carrying capacity thereby limiting the primary use as a normal transit mixer.

2. The self loading attachment works on a hydraulic system having several cylinders & directional valves. Any breakdown to the self loading attachment makes the self loading transit mixer useless.

• 3. Due to provision of the self loading attachment to the transit mixer, The self loading transit mixer itself has to move to & fro, forward & backward like a loader and collect all the, material from various directions. This seriously limits the production capacity of the self loading transit mixer when compared to a normal transit mixer.

4. Since the original transit mixer stands at one place while loading takes place and all the materials are brought to it, it is loaded in a very short period of time, however as mentioned above, the self loading transit mixer needs very high time for loading equivalent amount of raw materials compared to a normal transit mixer.

5. Due to scattered raw materials, the self loading attachment has to move to all directions which is impossible & not practical if mounted on a normal commercial truck. So a specialty automobile truck had to be developed for the self loading transit mixer. Which meant the end user could no longer has the choice of selection of the commercial truck. Also as mentioned above, the added weight & added power requirement of the self loading attachment resulted in less transportation capacity. Therefore the self loading Mixers today are available in only 2 & 4 cubic meter capacity while the widely used transit mixer is 6 cubic meter capacity. If the self loading transit mixers are to be made in bigger capacity, again it has to be made along with custom designed truck on which it has to be mounted.^; The most important drawback of the self loading transit mixers, that the material cannot be weighed accurately. The recent efforts .include a weight indicator getting signal from the oil pressure in the cylinders of the self loading attachment. However the variation is too high and it is only proportional calculation and not actual weighing of the ingredients like in a conventionally used concrete batching & Mixing plant. In a concrete batching & mixing plant; the materials are actually weighed on cumulative basis by means of load-cells indicating actual weight on weighing hopper or weigh belt. Also once the self loading bucket is filled completely and if the material is in excess, then the operator has to stop and remove the excess material from the loading bucket in order to maintain accuracy. This problem is typically due to the low capacity of the feeding bucket. Secondly in case of a lower fill in the bucket due to any reason, the operator has to correct the shortfall in following subsequent bucket fills, which cannot result in a accuracy level, maintained in a normal conventional batch mix plant. The said bucket of the self loading attachment has to be of less capacity when compared to the front end loader, as it has to be accommodated in the feeding hopper and has to run on the available horsepower. This in turn results in more loading cycles and loss of productive time. 9. Economically, since the self loading transit mixer with its self loading attachment has to be mounted on specially designed and manufactured truck, the cost of the machine is very high. The cost is still higher when we think about the capacity which is in no way comparable to that of a normal transit mixer.

[003.07] Also the Transit mixer mentioned in all the above prior arts, needed a hydrostatic drive specially designed so as to enable to effectively mix the concrete during transit with a variety of speeds and different directions of rotation of the drum without shocks. Further the hydrostatic drive used ensures that there is no damage to the driving gearbox due to frequent reversal of the rotating drum.

[003.08] The said hydrostatic drive has been used for years for this application and has gone under many refinements in order to increase the efficiency. Generally in hot condition, many older hydraulic drives operate at 50 to 60 % efficiency. However due to modern axial piston pumps the efficiency has been increased considerably over 80%. However that has also resulted in making the system highly expensive and complex compared to a normal mechanical drive which has minimum power loss and hence maximum efficiency close to-95%.

[003.09] However since the transit mixer needed variable speeds and opposite direction rotations, it was not possible practically over the last 60 years to have a simple mechanical drive with much higher mechanical efficiency for this application due to the complex requirement of the material under transport. The frequent change in directions and speed would require frequent disengagement of the engine to neutral position by means of a clutch before shifting the transmission into opposite direction. Also the frequent clutch operation could result into very low working life of the mechanical parts like the engaging plates and the transmission gears. Also the mechanical reversal of the direction would have resulted into high shock loads due to the inertia of tfie material under transport. These shock loads would have resulted into frequent damages to the transmission and the prime mover. To conclude, a transit mixer needed a hydrostatic transmission since it had to be operated frequently in variable speeds in opposite directions to control the charging and discharging of the material under transport.

[003.10] The biggest disadvantage of the transit mixer mentioned in all the three Prior arts as above is that it can transport & keep the concrete alive but it cannot mix dry materials & produce concrete as homogeneous as produced by a twin shaft mixer or a PAN Mixer Or any other proven mixer having forceful mixing. Rather the mixing depends upon the duration of transit. For example, the concrete produced by a twin shaft mixer is- more homogeneous due to the fact that it is mixed forcefully by a pair of shafts having multiple mixing blades and rotating in opposite direction: to each other, wherein each mixing blade is placed in a different angle so as to have a complete forceful mixing without depending upon gravitational force. However in a transit mixer the spiral blades whether single start or multi-start are unidirectional and all push the material in only one side depending upon the direction of rotation of the drum. The mixing is achieved by gravitational force due to the rotation of the drum which is not at all a force-full mixing.

[003.11] Another draw back of the rotating drum transit mixer is requirement of very high filling volumes. As mentioned above due to gravitational mixing, the transit mixer drums need to be provided with very high filling volumes than the actually mixed volume of the material. This is because during the rotation, the material needs a larger space to fall under gravity and get mixed due to that action. This makes the transit mixers very bulky equipment when compared to the actual volume under transport.

[003.12] Due to the closed drum design, it is very difficult" and pain-full to clean and break the hardened concrete inside the drum in cases of breakdowns, etc. If the concrete is set inside due to any reason, a person has to go inside the drum to break the set concrete with a hydraulic breaker which is a very painfull activity due to the closed interior and dusting resulting due to breaking.

[003.13] Hence due to its very design of rotating drum an l larger than required filling volume resulting due to its dependence on gravitational mixing, a transit mixer is a risky but unavoidable transporting equipment, :^■

[003.14] Hence there has been a long felt need to have a transit mixer which can be loaded directly by a front end loader, wherein all the materials can be actually weighed and could be used as a single mean for production as well as transportation of concrete without altering its capacity and could be mounted on a normal commercial truck chassis available in the market .

[004.00] SOLUTION TO THE PROBLEM / OBJECT OF THE INVENTION

[004.01] An Important object of the present invention is to provide a uniquely designed transit mixer which can : a) Be easily loaded directly by a normal widely available front end loader. b) Produce and transport concrete without any alteration in the capacity. c) Be mounted on a normal commercial truck chassis easily available in the market. d) Can actually weigh and forcefully mix all the ingredients. e) Can be loaded in a very short period of time. f) Be very simple in construction for use & maintenance. g) Be made in various capacities and can be mounted ^' on trolleys/trailers or commercial trucks depending upon the requirement of the end user. h) Be driven by a simple mechanical drive with optimum efficiency and at a lower capital and running cost. i) Be driven in only one direction for mixing as well as discharge avoiding the frequent reversals of directions.

[004.02] Another object of the present invention is to provide a user friendly apparatus for production of concrete which is highly cost effective as it can produce & transport concrete as a standalone unit with a widely available front end loader to replace the conventional system without the disadvantages of the self loading transit mixers.

[004.03] One more important object of the present invention has been to impart the right of selection of the commercial truck to the end user

[004.04] One more important object of the present invention has been to eliminate requirement of specialty vehicle for its mounting and therefore reducing the end user's dependency.

[004.05] One more important object of the present invention is to enable loading by a front end loader by keeping the transit mixer at one place unlike the self loading transit mixer, resulting in reducing the material loading time.

[004.06] One more important objective of the present invention is to have higher productivity along with optimum transportation capacity by eliminating the dead weight of the self loading attachment. [004.07] One more important objective of the present invention is to ensure a reliable operation by limiting the no. of moving parts to only one. Unlike the self loading transit mixer, which cannot be loaded by another loader if its own self loading attachment is under breakdown.

[004.08] One more important objective of the present invention is to use the material stocking place available at site to optimum advantage.

[004.09] One more important objective of the present invention is to have an apparatus having a very less loading height and which can be loaded with widely available front, end loaders without any major ramp or site modification.

[004.10] Further an object of the present invention is to reduce the cost of production of concrete by simplifying the equipment & the process.

[004. 1] Another object of the present invention is to provide a unique apparatus which can be produced in capacities according to the standard trucks available.

[004.12] An added object of the present invention is to provide an equipment which is simple in construction and offer a very high advantage over the self loading transit mixers in flexibility & in capital cost.

[004.13] Further an object of the present invention is to provide an equipment which is - efficient in operation and can be used in different ways by different users to produce concrete. It can be used to produce concrete on weight as well as volume basis.

[004.14] Another object of the invention is to provide a unique apparatus which can alternatively mounted on a trolley/ trailer and can be transported even in congested city traffic. [004.15] Another object of the invention is to provide a unique apparatus which can forcefully mix the dry materials due to provision of bi-directional mixing spirals and produce concrete like any other forceful mixer.^'

[004.16] Another object of the invention is provide a more compact apparatus by reducing the un-necessary filling volume as mixing is achieved due to forceful bi-directional movement of the material under transport due to the unique and novel design of the rotating spiral blades.

[004.17] Another object of the invention is to proved an equipment which is easy to clean and stable to transport due to its Stationary Concrete Mixing Drum Design.

[005.00] DISCLOSURE OF THE INVENTION:

In accordance with the present invention there is provided a "Novel SCMD Transit Mixer for Production & Transportation of Concrete". The present invention is called Novel because of the following reasons:

[005.01] Novelty of design : The said apparatus is adopted with following novel features which are radically different & never used in any of the prior arts: a. The concrete mixing drum :

While all the prior arts are using rotating drums, the said apparatus is provided with a Stationary Concrete Mixing Drum, hereinafter called the SCMD. Further the SCMD is provided with an opening at the top to. enable a front end loader to load it directly unlike any of the prior arts. It is provided with a protective cover during transit. b. The central rotating shaft :

Unlike any other prior arts, The SCMD is provided with a central rotating shaft on which the mixing and discharging spirals are attached. c. Single direction rotation for mixing as well as discharging :

Unlike any other prior art or existing transit mixer, the said apparatus is provided with¹ only a single direction of rotation/ Thus both the functions of mixing & discharging are achieved with a single direction of rotation and no reversal of direction is required. This feature is completely novel and no existing transit mixer is operated with only one direction of rotation. d. Unique arrangement of Mixing & Discharging blades :

In all the prior arts, same spiral blades are used for mixing in one direction and discharging in another, However in this apparatus two different sets of LEFT HAND & RIGHT HAND spiral blades are attached^' to a single shaft. Both sets of spiral blades are different in dimensions from each other and different in construction. The larger diameter spirals are called DISCHARGING SPIRALS and the smaller diameter spirals are called MIXING SPIRALS. However both contribute to homogeneous & Cyclical forceful mixing when the gate is closed unlike any other prior art. e. Bidirectional movement of material with unidirectional rotation of the single shaft :

This impossible sounding movement is achieved by using LEFT HAND & RIGHT HAND construction spirals mounted on the same single shaft. When the shaft is provided with a unidirectional rotation, the LEFT HAND spirals push the material in opposite direction to that of the RIGHT HAND spirals. Hence a bidirectional movement within the material under mixing is achieved with a unidirectional rotation of the said single shaft. This concept is new & never used in the history of concrete mixing or transportation. f. Possibility of accommodation of Mechanical drive:: As mentioned earlier all the existing prior art transit mixers could not accommodate mechanical drives or direct drives as they needed frequent reversals of directions causing heavy shocks and have to use hydrostatic drives to avoid damages. However since the said invention does have only one direction of rotation for both mixing & discharging functions, it does not require any reversal of direction. The mechanical drive;; makes the invention very economical by eliminating the hydrostatic drive and also saves the running cost by improving the mechanical efficiency to comparatively higher level minimizing the power loss. A reduction gearbox with very high reduction ratio is provided to drive the single shaft ensuring a very; high output torque wherein the output rpm of the said single shaft is varied between 8 to 14. The variation of output rpm is simply achieved by variation of the engine rpm. The high reduction ratio of the gearbox enables the engine to even start under load if required. g. Optional Weighing feature :

When the Concrete is to be produced on weight basis the entire assembly is supported on electronic load-cells which display the exact weight of the material inside the SCMD on a digital weight indicator, Since the batch size is very large, a better accuracy can be easily maintained. A novel quick locking arrangement made with the help of pivot pins and locking wedges keep the load-cells protected during transit and ensure the stability of the equipment throughout. The apparatus is made without load-cells if it has to be used only for transportation or for transportation & mixing of concrete on volume basis.

[005.002] The said "Novel SCMD Transit Mixer for Production & Transportation of Concrete"" typically consists off the following components: A steel fabricated Stationary Concrete Mixing Drum ' hereinafter called "SCMD", open on the top for loading even by a front end loader and provided with protective cover during transit. b. A Rotating set of small diameter spiral blades in the form of continuous ribbon hereinafter called "MIXING SPIRALS" mechanically attached or welded by means of arms to the central rotating shaft inside the SCMD. [ c. A rotating set of larger Diameter Spiral Blades in the form of continuous ribbon hereinafter called " DISCHARGING SPIRALS" mechanically attached or welded by means of arms to the same said shaft inside the SCMD. d. A mechanical drive directly coupling the engine with a reduction gearbox driving the said single shaft to improve the mechanical efficiency further for optimum use of horse-power. Typically the engine & gearbox are coupled though a pair of knuckle joints to allow angular alignment. The above mentioned reduction gearbox is typically provided with a very high reduction ratio so as to provide a variable speed of rotation between 8 to 14 rpm of the said single shaft. Alternatively can be adopted to be driven with a hydrostatic drive. e. A single shaft thus having two different sets of simple Archimedean or modern screw spiral blades having replaceable liners running throughout the length of the mixer as explained in point b & Point c which are subjected to rotation. f. A controlled discharge gate of suitable size towards the opposite end of the SCMD. g. A steel fabricated channel structure on which the SCMD is mounted at an inclined angle similar to a transit mixer. h. A suitable capacity water tank with a water punip having been taken drive through the same slave engine or alternatively - from a hydraulic motor or alternatively by gravity without pump. i, A semicircular bottom wall of the SCMD throughout the length of the mixer drum ensuring uniform gap in the spirals and the wall. j. A set of high capacity, shockproof, electronic load cells on which the SCMD is supported to carry out actual weighing of each ingredient loaded in to the mixer while producing weight based concrete. The load - cells transmit the accurate weight of the contents of SCMD to a digital weight Indicator. Alternatively the load-cells are not provided when the concrete is to be produced on volume basis or when the invention is used only for transportation. ^■? k. A suitable but heavy duty quick locking arrangement to protect the load-cells & to ensure stability during long transit. Alternatively the quick locking arrangement is not provided when concrete is to be produced on volume basis or when the invention is used only for transportation.

I. A platform to keep extra cement bags. - rru A rotatable discharge chute with mechanical height adjustment suitable for ' feeding the concrete pump directly. n. An optional chute for loading by a stationary Concrete plant.

[005.01] Typically, the said ""Novel SCMD Transit Mixer for Production & Transportation of Concrete"" is provided with a Stationary Concrete Mixing Drum which is open on the top to enable loading of all raw materials. Most importantly it is provided with a loading height suitable for a widely available front end loader to load the ingredients directly. Water & cement ar also loaded through this opening.

[005.02] Typically, the said ""Novel SCMD Transit Mixer for Production & Transportation of Concrete"" is adapted to weigh the solid & liquid constituents by positive weight gain in a cumulative way when producing concrete on weight basis. For example while loading to a full capacity of 6 cubic meter, typically all the quantity of each ingredient is added at one single time by the front end loader. While producing concrete on weight basis, water & cement are added^' first to have maximum accuracy.

[005.03] Typically the water & cement is added to the. mixer simultaneously with the aggregates to save further time when producing concrete based on volume. Typically, the solid constituents are typically stones or gravels, fine particles, cement and fly ash, said stones or gravels are of various size, said fine particle includes stone dust or river sand.

[005.04] Typically, during rotation, the said MIXING SPIRALS are pushing the material in a direction opposite to that of the DISCHARGING SPIRALS, even though the shaft is rotating in only one direction. This opposite movement of material is achieved by using LEFT HAND & RIGHT HAND Screw Spirals. During the unidirectional rotation of the said shaft, the DISCHARGING SPIRALS always push the material towards the discharge gate. However at the same time the centrally placed MIXING SPIRALS push the material towards the opposite direction providing a quick relief and forceful mixing. A variable speed of rotation in a lower output rpm range is provided to ensure optimum output torques. The speed of rotation can be increased for quick discharging or quick Mixing. In the case of mechanical drive, the prime mover is directly connected with a heavy duty reduction gearbox and the speed is controlled by increasing or reducing the engine RPM which is a marginal variation given the lower output rpm range.

[005.05] Typically, the novel SCMD Transit mixer is driven by a small capacity dedicated slave engine connected directly to the reduction gearbox as mentioned above. Alternatively when the drive from the truck PTO is available it is driven by directly coupling the PTO shaft with the reduction gearbox ensuring proper input rpm.. Typically the trolley mounted mixers are driven by a dedicated slave engine. Alternatively to minimize the effect of engine vibration on weighing accuracy, it can be driven by a hydrostatic drive having the engine & pump assembly mounted on a different frame. Alternatively it can be driven by an electric motor through an alternator driven by a slave engine or by PTO shaft. ; .

[006.00] CONSTRUCTION, WORKING & DETAILED DESCRIPTION WITH

REFERENCE TO THE DRAWINGS ENCLOSED: CONSTRUCTION :

The said "Novel SCMD Transit Mixer" is hereinafter described with reference to the drawings enclosed.

The said "Novel SCMD Transit Mixer" (01) is as shown in the drawing. It consists off a Stationary Concrete Mixing Drum (02) kept in Inclined condition having a opening (03) at the top on a steel fabricated framework and suspended/supported on optional electronic load-cells (04). A single shaft (05) having provided with a set of simple Archimedean or modern screw spiral blades having a bigger outer diameter called DISCHARGING SPIRALS (06) runs throughout the length of the said SCMD. The same shaft (05) is also provided with another set of simple Archimedean or modern screw spirals having smaller outer diameter called the MIXING SPIRALS (07). The bottom of the mixing device is made semi-circular. A uniform gap is maintained between the bottom wall & the helicoids to ensure that the materials are pushed forward by screw action. The helicoids spirals (06) are converted into continuous ribbon which allows through mixing of ingredients.. The single shaft (05) is driven by a heavy duty planetary gearbox (09) having a very high reduction ratio specifically operating at a low RPM generating high output torques in output speed range of 8 to 14 rpm. On the other end of the SCMD a controllable discharge gate (10 ) is provided. A suitable capacity water tank (12) is provided along with the water. pump(11) not visible in the drawing. A rotatable discharge chute (13) is provided for direct feeding into the concrete pump hopper. A quick locking arrangement (14) is provided to protect the load-cells during transit. A digital weight Indicator (15) is provided to display the exact weight of the contents of the SCMD. A slave engine (16) is coupled with the said reduction Gearbox (09) through a pair of knuckle joints.

When the equipment is used only for transportation / production of concrete on volume basis, the quick locking arrangement after locking shall make the load-cells redundant.

[006.01] WORKING OF THE SAID "Novel SCMD Transit Mixer": The said novel SCMD Transit Mixer (01 ) is loaded by a front end loader through the opening (03) provided on the top of the Stationary Concrete Mixing Drum(02). Each material is added cumulatively for the entire capacity. The Weight of the material is clearly displayed on the digital weight Indicator (15). The batch size is big enough to have more tolerance and hence greater accuracy for each material. Under rotation, the said shaft (05) is provided with only one direction of rotation. While the shaft rotates, the DISCHARGING SPIRALS (06) continuously push the material under mixing towards the discharge gate which is mechanically closed. Simultaneously at the same time the material reaching the extreme end above the discharge gate(10) is continuously pushed in opposite direction by the MIXING SPIRALS (07). This ensures that there is no deadlock and also ensures cyclical mixing throughout. The DISCHARGING & MIXING SPIRALS (06) & (07) are designed to have specific pitch dimensions and specific ribbon width to ensure that rate of push implied by each set of spirals is approximately equals to that of another. This ensures that there is no material imbalance in any side of the mixer. After loading is complete, the quick locking arrangement (14) is put in place. The Quick locking arrangement is made up of pivot pins & support plates with quick locking wedges not shown in the drawing. The Quick locking arrangement ensures complete protection to the electronic load cells during transit. The quick locking arrangement (14) also ensures complete stability of the vehicle under transport. During transport, the rotation speed of the shaft (05) is reduced considerably only keep the mixed concrete alive. After reaching the place of pour, the discharge gate(10) is opened. Mixed concrete is discharged forcefully by the continuous forward discharging action of the DISCHARGING SPIRALS (06). When the discharge gate(10) is open, the materia! forwarded by the DISCHARGING SPIRAL (06) does not surge and escapes through the discharge gate. This continues till the entire material is completely discharged. The material being discharged is then placed in a concrete purnp or at the place of pour through rotatable discharge chute (13).

1006.02] The SCMD Transit Mixer produces concrete on weight basis or on volume basis as disclosed above. When producing concrete on weight basis, all the ingredients are added into the SCMD one by one and the weight readings are displayed on the digital weight Indicator. The spiral blades are provided under very slow rotation while the materials are added to the SCMD one by one. During Mixing & transporting the DISCHARGING SPIRALS and the MIXING SPIRALS push material in opposite direction however the shaft rotation is unidirectional. ^

The weighing is carried out on cumulative basis as each material is loaded. [006.03]Example for quick loading of 6 cubic meter (full, capacity) of concrete into the Novel SCMD transit mixer :

The mix design given for one cubic meter is multiplied by 6 for each ingredient so as to load each ingredient cumulatively. For' example, if one cubic meter design has1 100 kg of sand, then for six cubic meter, total sand needed is 6600 kg. which is loaded at once by the front end loader. Since the tolerance for aggregates is plus or minus 3 %, it can be easily achieved as due to the larger fill the tolerance limit is around 198 kg. Cement can be added by actually unloading the bags with manuaMabour or by a screw connected to a manual feed hopper or silo in case of bulk cement. Thus the loading is astonishingly quick and highly accurate due to larger batch size compared to the self loading transit mixer,

[006.04]While producing concrete on volume basis, all the. materials are added to the SCMD simultaneously reducing the loading time.

[006.05]During the transit, a heavy duty quick locking mechanical arrangement is provided to ensure road safety as well as protection ^' to the load-cells. The load- cells provided are as per the load capacity of the Transit mixer with necessary safety margins to take loads more than specified as per mixer capacity.

[006.06JA protective cover is provided on the SCMD to av id rain water entry into the SCMD, Below the protective cover, a steel fabricated mesh is provided on the top of the SCMD to prevent boulders entering into the SCMD.

[006.07] Other aspects of the invention will become apparent by consideration of the accompanying drawing and their description stated above, which is merely illustrative of a preferred embodiment of the invention and does not limit in any way the nature and scope of the invention.

Figure 1 illustrates the said "PRIOR ART N0.1" & PRIOR ART NO 2. in accordance with the present invention; The only difference in the construction of prior art No.1 which is a normal transit mixer & Prior art No. 2 which is a dry:_:mix or transit mix truck is the construction of inner spirals especially single or multi start spirals. Figure 2 illustrates the said "PRIOR ART NO. 3" which is a self loading transit mixer with a self loading bucket with swiveling action provided in addition to rotation of drum; in accordance with the present invention;

Figure 3 illustrates the said "Novel SCMD Transit Mixer" in accordance with the present invention; ^'■<,

Figure 4 illustrates arrangement of MIXING & DISCHARGING Spirals in the said "Novel SCMD Transit Mixer" in accordance with the present invention;

[007.00] ADVANTAGEOUS EFFECTS AND ECONOMIC SIGNIFICANCE

The present invention brings a huge advantage to the industry by providing an equipment which can produce and transport concrete. The said invention uniquely meet following achievements compared to the conventional methods & means described in the prior art:

[007.01] It can be directly loaded by a widely available front end loader and does not require a concrete batching plant as it carries out. accurate weighing itself due to more tolerances due to larger batch size compared to a stationary Batching plant, Typically a 30 cubic meter per hour capacity plant is provided with a batch size of ,0,5 cubic meter of concrete. While In case of the said invention the batch size may range between 1 to 12 cubic meter depending upon the capacity of the mixer. The invention can also transport the concrete and do not require separate transit mixers. It therefore reduces the production cost of concrete by almost 50-55%.

[007.02] It can be mounted on normal commercial trucks as per capacity, as per the end user's choice and no specialty truck is required for its mounting, which also brings huge flexibility and huge reduction in capital cost.

[007.03] It can produce & transport same amount of concrete when compared to a normal conventional transit mixer mounted on equivalent truck unlike a self loading transit mixer.

[007.04] It has very less moving parts & very simple design which results in less running

& maintenance; cost. Moreover the moving parts are open for cleaning & maintenance unlike normal transit mixers. [007.05] Since the invention completely eliminates the need of stationary Concrete production plants & conventional transit mixers, it results in huge reduction in the capital cost. Also it saves the otherwise dead investment into land & foundations required, for installation of the stationary plants. It also eliminates the high dedicated source of power which is otherwise required to operate the plant and reduces the running cost and saves; diesel fuel. This results in a unique user_:friendly product which also offers a huge benefit in the running cost as the net power used for production & transportation of one cubic meter ' of concrete is very very low compared to the conventional system.

[007.06] It can be made in various capacities to suit the requirement of the end user and can be mounted on a trolley or trailer or a commercial truck depending upon the choice of the end user unlike the self loading transit mixers.

[007.07] Since it can be loaded directly with a normal widely available loader, the end user can have the flexibility to do the loading either manually or by one loader or by two loaders depending upon his own output requirement. For short terms he can also take the loader on monthly or daily rent.

[007.08] Since the equipment can also be mounted on small trolleys towed by tractors, a small tractor loader can be used for the dual purpose of loading as well as transportation.' Apart from flexibility, the capital cost of the total combination is less than 50% of the equivalent capacity self loading mixer on specialty vehicle,

[007.09] Thus the said invention actually eliminates the conventional system of stationary batching plant with transit mixers unlike the self loading transit mixer, and eliminates the investment in land & foundations, captive power source and transportation cost associated with the conventional system.

[007.10] The said invention enables the front end loader to directly load itself thereby ensuring optimum utilization of the material stocking.area.

[007.11] The said invention has a much lower manufacturing cost due to its simple design and hence is easily affordable, compared to any of the prior arts.

The said invention therefore results in huge saving of the very important natural resource of diesel fuel required for production of concrete per cubic meter, [007.1 ¾ UNLIKE ANY OTHER EXSISTING TRANSIT-MIXER/ self loading mixer Or any other prior art, the biggest advantage of the said invention is that it eliminates the need of the conventional system of stationary plants & transit mixers. It brings a huge flexibility and economy to the production of high quality concrete as it can be directly loaded by a normal widely used front end loader. It can ensure accuracy of weighing due to the larger batch size & because of actual weighing unlike a self loading mixer. It can be used for production of any capacity of concrete whether stationary or mobile application. It reduces the emissions by having very little moving parts. It is a revolutionary concept which will change the way concrete is produced and sold. Therefore the invention has a very big economic significance as it will reduce the capital cost of all types of constructions whether infrastructure or Mass housing.

[007.12] While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments; it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted ^merely as illustrative of the invention and not as a limitation.

Claims

[008.00] We Claim:

1. A highly compact "novel S.C.M.D. transit mixer for production & transportation of concrete " which has a Stationary Concrete Mixing Drum with a open top, to enable a front end loader to load it directly .wherein the SCMD is supported or suspended on a plurality of optional electronic load-cells and enclosed by a steel fabricated framework & provided with a unique set design of mixing & discharging spirals ; said device comprising with : a. A steel fabricated Stationary Concrete Mixing Drum hereinafter called "SCMD", open on the top for loading even by a front end loader and provided with protective cover during transit. b. A Rotating set of small diameter spiral blades in the form of continuous ribbon hereinafter called "MIXING SPIRAL" mechanically attached or welded by means of arms to the central rotating shaft inside the SCMD. c. A rotating set of larger Diameter Spiral Blades n the form of continuous ribbon hereinafter called " DISCHARGING SPIRAL" mechanically attached or welded by means of arms to the same said shaft inside the SCMD. d. A mechanical 'drive directly coupling the engine with a reduction gearbox driving the said single shaft to improve the .mechanical efficiency further for optimum use of horse-power. Typically the engine & gearbox are coupled though a pair of knuckle joints to allow angular alignment. The above mentioned reduction gearbox is typically provided with a very high reduction ratio so as to provide a variable speed of rotation between 8 to 14 rpm of the said single shaft. Alternatively can be adopted to be driven with a hydrostatic drive. e. A single shaft .thus having two different sets of simple Archimedean or modern screw spiral blades having replaceable line/rs running throughout the length of the mixer as explained in point b & Point c which are subjected to rotation. f. A controlled discharge gate of suitable size towards the opposite end of the SCMD. g. A steel fabricated channel structure on which the SCMD is mounted at an inclined angle similar to a transit mixer. h. A suitable capacity water tank with a water pump having been taken drive through the same slave engine or alternatively from a hydraulic motor or alternatively by gravity without pump. i. A semicircular bottom wall of the SCMD throughout the length of the mixer drum ensuring uniform gap in the spirals and the wall. j. A set of high capacity, shockproof, electronic load cells on which the SCMD is supported to carry out actual weighing of each ingredient loaded in to the mixer while producing weight based concrete. The load cells transmit the accurate weight of the contents of SCMD to a digital weight Indicator. Alternatively the load-cells are not provided when the concrete is to be produced on jvolume basis or when the invention is used only for transportation.■ . k. A suitable but heavy duty quick locking arrangement to protect the load-cells & to ensure stability during long transit. Alternatively the quick locking arrangement is not provided when concrete is to; be produced on volume basis or when the invention is used only for transportation.

I. A platform to keep extra cement bags. m. A rotatable discharge chute with mechanical height adjustment suitable for feeding the concrete pump directly. n. An optional chute for loading by a stationary Concrete plant.

2. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically provided with a controllable discharge gate.

3. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete " as described in claim one, wherein the said device typically uses a shaft with two sets of L,H. & R.H, spiral blades in the form of continuous ribbon centrally supported by the said single shaft.

4. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically provided with a Stationary Concrete Mixing Drum suspended ^:or supported on electronic load-cells. :^!

5. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically provided with a stationary Concrete Mixing Drum with an opening on the top to enable material loading by a widely available front end loader.

6. The said "novel S.C.M.D. transit mixer for production & transportation of concrete " as described in claim one, wherein the said device is typically alternatively provided with forward & reverse direction and rotating shaft having only discharging spirals which act as mixing spirals in reverse direction and discharge in forward direction through an uncontrolled discharge gate. Alternatively the Discharging Spirals as mentioned are shaft-less spirals.

7. The said "novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim orie, wherein the said device is typically alternatively provided with a hydrostatic drive by a dedicated slave engine or alternatively an electric drive through an electric motor driven by alternator coupled with a slave engine.

8. The said "novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically provided with a mechanical drive as the slave engine is directly coupled to the reduction gearbox.

9. The said "novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically alternatively provided drive by a propeller shaft directly coupling the reduction gearbox and the PTO shaft of the truck on which it is mounted. Alternatively the drive is given through a belt & pulley arrangement when input rpm of the PTO shaft needs adjustment. ·

10. The said "novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically alternatively provided with a FNR Gearbox between the truck PTO or slave engine & the reduction gearbox.

11. The said "novel S.C.M.D. transit mixer for production & transportation of concrete " as described in claim one, wherein the said device is typically provided with a rotating shaft having ^unidirectional rotation however the Discharging Spirals and The Mixing Spirals attached to the same shaft, push the material in opposite directions. This is achieved by using Left hand and Right Hand spirals.

12. The said "novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said shaft with spirals is typically provided with a single direction of rotation for mixing as well as discharging unlike a normal transit mixer.

13. The said "Novel, S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the drive is typically taken from a dedicated slave engine or alternatively from the truck or tractor PTO. When operated electrically the PTO drive is used to generate power through an alternator which operates the device through an electric motor. Alternatively When operated hydraulically the PTO drive is coupled with a hydraulic pump which operates a hydraulic motor through an oil cooler with or without a directional control valve. ;^{■ . .}

14. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the simple Archimedean spirals provided are typically converted into continuous ribbon. Alternatively they are replaced by intermittent spiral blades or kept as it is.

15. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is provided with a Stationary Concrete Mixing Drum suspended or supported on suitable capacity electronic load cells which transmit the weight through ¾ digital weight Indicator. The weight indicator is provided with a printer output. .

16. The said "Novel S.C.M.D. transit mixer for production X transportation of concrete" as described in claim one, wherein the said device is used without load- ceils for only transportation OR production & transportation of concrete produced on volume basis.

17. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein weighing is carried out either when spirals rotation is on or in static condition.

18. The said "Novej S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically adapted to actually weigh the solid constituents by positive weight gain principle.

19. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device alternatively uses a separate weigh hopper or a weighing belt suspended or supported on the top of the Stationary Concrete Mixing Drum.

20. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device alternatively uses a plurality of hoppers on the top of SCMD to form a batching plant with positive or negative weighing system & is used with or without truck or trolley.

21. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically mounted on trolleys and towed by a tractor. ,

22. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is typically mounted on a suitable capacity commercial truck.

23. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as- described in claim one, wherein the said device is loaded either manually or directly; by a front end loader.

24. The said "novel S.C.M.D.. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device in isolation is used as a portable batch-mix plant.

25. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is alternatively adopted to use a rotating reversible drum with a separate feed hopper to enable loading by a front end loader & the drum supported or suspended on electronic load cells.

26. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device is alternatively adopted to use rotating multiple start spirals & separate flights provided with forward or reverse direction inside a stationary Concrete Mixing Drum.

27. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device alternatively uses a separate weighing system for more accurate weighing of cement.

28. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device typically uses the SCMD in an inclined position however alternatively is used to adopt SCMD in a horizontal position.

29. The said "Novel S.C.M.D. transit mixer for production & transportation of concrete" as described in claim one, wherein the said device alternatively uses a hydraulic cylinder powered by a hydraulic power pack or through the slave engine or through the PTO to assist discharging by lifting the SCMD like a dumper.