|Title of Invention||
REAR BALLAST FOR A TRACTOR
|Abstract||TITLE: REAR BALLAST FOR A TRACTOR ABSTRACT:" In the invention a concrete ballast comprising a relatively strong thick outer annular ring shaped shell integrally pre-formed defining an interior space within, filled with filler material and having an outer surface defining a desired outer shape of the ballast, and having spaced apart openings on the surface of the shell for receiving filler concrete material; alongwith means to secure the ballast to the wheel surface.|
FIELD OF INVENTION :
The invention is relating to the rear ballast of an agricultural tractor which is used to achieve efficient traction & thereby good crop productivity.
Tractors are powerful potentially lethal vehicles. Even a small tractor has a relatively high center of gravity and a narrow wheel base which makes it top heavy. The tremendous traction and pulling power of low gears, which enable the tractor to power up or across a steep slope, multiplies the potential for tripping over or doing a back flip, especially when pulling heavy implements or trailers.
Two types of ballast are commonly used for traction. Cast iron wheel weight can be mounted or removed. Liquid ballast must be usually be pumped by a tire service company. Optimizing ballast results in fuel saving.
The tractor ideally should manage power, ballast and tire inflation pressure. Pulling an implement at higher speeds reduces both drive train wear and soil compaction when the tractor is properly ballasted. It should be ballasted to achieve just enough traction to transmit power to ground without excessive wheel slip. Some power is always lost to wheel slip. Ballast may be distributed between front and rear of tractor in appropriate proportions to achieve maximum tractive efficiency and stability. Weight transfer is especially evident on two wheel drive tractor when the front end becomes so light that steering becomes difficult.
A, Over ballasted tractors compact the soils, squeeze soil particles closely together and reduce pore space crops grown in soils damaged by compaction are less likely to survive moisture extremes such as heavy rain and droughts. Proper tire inflation and ballast minimize the forces applied to the soil surface, which minimizes the compaction and improves long term productivity of the soil. An optimum configuration of ballast and tire pressure is generally a compromise between maximum power transfer and acceptable levels of soil compaction.
Tractors are designed to transmit large amounts of power to the soil. Transmitting the power requires large friction or traction at the soil surface. Traction can be increased by increasing either weight or contact area. Additional weight creates greater forces at the soil surface, causing greater soil compaction and increased soil strength. The increased soil strength resists the forces applied by a tire as it transmits power to implements in contact with the soil, but additional weight causes a deeper track, which increases rolling resistance. Wide tires and dual tires increase contact area, flotation and traction and reduce both depth of track and compaction.
Extra compaction of soil can cause a physical barrier to normal healthy root growth, causing symptoms of water stress and nutrient stress. The effects of reduced pore are reduced water infiltration, water holding capacity and air exchange.
When moisture is neither in short supply or excessive, the pore space in a well structured soil acts as a reservoir and conduit system for water, buffering the effects of moisture extremes. An ideal soil is composed of balanced pore space allocated equally to air and water. Pore space also allows roots to displace soil as they grow. Compaction restricts the crop growth. Maximizing tractive efficiency & minimizing compaction are often compatible goals and both increase profitability.
B. Correct ballasting will also avoid accidents and improve productivity.
Heavy implements mounted on the front or rear of the tractor requires corresponding ballast at the other end of the tractor.
Due to over ballasting or under ballasting, the wheels will bounce off the ground. The balancing of ballast in front is to have enough weight to keep the wheels on ground, but without so much weight that steering is difficult.
In four wheel drive, the weights are generally evenly split between front and rear. However on a two wheel drive tractor the weight is concentrated on the rear axle to improve the traction.
Suitcase weights on a bracket are the usual weights on the front. For tractor with front loads and no regular implement on the rear, a bracket for weights or a concrete weight with pins for the 3 -point hitch will level the loading.
Rear ballast can be done with liquid fill in tires or with wheel weights and is determined by the wheel slip.
The performance of the tractor is generally improved by ballasting the tractor properly. These will involve adding or removing weight corresponding to the actual need.
Overall weight and weight distribution are important for traction, stability, safety and soil compaction. The tractor ought to be light to minimize soil compaction, yet be heavy enough to do the job. More weight on tires will increase the tractive force available for pulling. More weight on the front wheel will reduce the tendency to overturn to the rear.
Small compact tractors are more useful as the increased speed reduces the weight needed to provide the traction efficiently and therefore also reduces the pressure applied to the soil and in turn soil compaction.
Tractor can be managed with desired ballast. The ballast is added in two ways. The tires are filled with Calcium Chloride, antifreeze, water or metal weights attached to the tractor. The most common area to add metal weight is tractor rear wheels. The chosen location will depend on the configuration of the tractor. A two wheel drive tractor will require 65% - 75 % of the weight on the rear wheels whereas 4 wheel drives requires 40% - 45% of the weight on the rear wheels.
However adding too much ballast will increase the depth of the tire track and rolling resistance. Therefore, it becomes a balance between adding weight to reduce wheel slip while not adding too much to create exercise rolling resistance.
Generally most tractors have provision for adding weights on the front and are Cast Iron with a handle cast in. Most tractors can handle plurality of these weights. These are
called suitcase weights as you can lift them on & off by the handle. Once in place, they should be locked down in some manner, typically by a rod through the handle holes or other holes. Front end weights help counter balance the weight of rear implements.
When the implements are lifted, and contribute to traction when weight transfer under load effectively moves part of the weight to the rear wheel. They can thus contribute to traction stability and safety at very inexpensive in cost.
Generally Cast Iron weights are readily available to mount on the wheels, more commonly on rear wheels. Rear wheel weights add weight directly to the rear axle. However, though effective are not as easy to add or remove as front end weights. The tendency is to install them and forget them. Thus the weights are in place even when not needed.
Another way commonly known is to never fill the tire with fluid with room for an over the fluid. The air will provide the cushioning. Plain water may be used, however selection of Calcium Chloride washing more is preferred, it also acts as antifreeze. This means fluid cannot be altered easily to suit current needs at different times.
Generally when a tractor is a front end load loader, a cast iron or concrete counter weight is added.
Proper ballasting means tractor should be easy to steer, improve traction and improve stability, however it will increase the soil compaction and stresses on axles and tires. The ballast should be adjusted for most efficient configuration such that it shall result in fuel cost due to the efficiency.
Liquid ballast have the disadvantage of non-removability easily. The liquid ballast weights is so permanent and also some of them may accelerate rusting and corrosion of steel wheels themselves.
Cast iron weights is easily added or removed. Weights save you from repairing many flat tire since any tire sealant can be added to tire, which is not available when liquid ballast is used.
Generally rear wheel metal weights can be manually or jack lifted to the rim and bolted into position.
Generally carriage bolts, lock washers and nuts are used to mount the first wheel weight. The carriage bolts which fitted on the first weight before it is attached to the rim, so that the next weight added will have an attachment points First weight is then tightened in position to the rim. The second weight will have also carriage bolts.
Basically each of the additional weights is daisy chained off of the first weight that is securely bolted to the wheel rim. Second weight is now tightened in position to the previous weight. There are two extra carriages for the next weight.
When adding or removing ballast especially to front weight bracket because it is not centered over the front axle, reduces the weight on rear axles. For example adding X kg on front increases total tractor weight by X Kg but may increase the weight on front axle by X + Y Kgs and reduce the weight on rear axle by Y Kgs.
The static no load weight distribution should be maintained and referred while adding and removing ballast from the front and rear of the tractor.
Front wheel assist and four wheel drive tractors should have relatively more weight on the front than 2 wheel drive tractors because the front wheels also proved traction.
The tractor jumps or bounces during field operation and creates a very uncomfortable ride and loss of traction. Operator may need to shift to a lower gear, reduce throttle or raise implement to continue operation. To control the power hop, tires are inflated/ deflated along with addition/reduction of weight on the axle.
OBJECTS OF THE INVENTION
Careful management of ballast and tire inflation can maximize tractive efficiency, minimize compaction, increase tractor drive train, life and increase profitability. It is attempted to make use of cheap concrete and achieve a good ballast.
DESCRIPTION OF INVENTION ;
The ballast weight as per the invention is generally an annular ring concrete block and having 3 radial strengthening steel rods embedded within, at equidistance. The innovative approach is to replace the cast ballast weight while retaining the simplicity.
A concrete ballast is disclosed wherein the ballast is formed as integral solid cement ring enclosed with an annular polymer ring, the polymer ring also formed as a integral shell by roto-moulding process with one shell U shaped cross section & an another shell of flat surface to form a single annular hollow ring, which hollow ring is filled with concrete mixture through filling holes which are then capped with pure cement mixture. The U shaped cross section shell may be extended to any other suitable shape and configuration.
To construct ballast with metal and solid concrete by casting is known. However none of the products or the patents deal with any particular construction of ballast for tractor. They do not relates to the use of polymer outer shell member nor do they relate to any particulars type or shape of the pre cast forms.
In the invention, the shell is made in sections which may be assembled or as integral shell pre-formed. When in sections, each shell section is formed in two parts, which are fixed opposite one another and bolted together or sealed together.
Each part of the shell section is formed with transversely extending end pieces to form a solid end to the section wherein assembled and the bolts are passed through holes provided in the end pieces. Thus the shell members are secured together. However the body of shell has holes, so that the shell can be filled with concrete mixture and the core concrete filled is left to set. It is envisaged that core concrete does not generally adhere to the shell member, thereby shell member acting as a reinforcing shock absorber to the core and providing weatherproof environment to the core. However if even the core is to adhere to the shell, then the core when filled acts as a unitary structure and does not suffer from any disadvantages due to this adhesion.
The problems overcome in this invention, is that polymer shell will prevent the core concrete filler from deterioration with time by the action of weather and dirt. Furthermore, in the invention, the only exposed area is the filler openings, which may not exceed 3-4 numbers, which means the unit is safely sealed. Further the sealed ballast needs to be secured to wheel vide 3 or more holes only, and nothing beyond, leading to simplified assembly at site. The secured means may be bolts, which can be protected from deterioration by means of known white plastic inserts or grouts or any equivalent product. In the invention, the end pieces at the peripheral edges, ensure stability to the shell members when assembled with each other and also ensures stable robust fixture to the wheel disc. The pre-forming procedure of the shell member including the end pieces is very simple, one of it being by roto-moulding process and the end piece may also add weight to the ballast.
The another advantage of this invention is that shell members can be designed to the requirement and the filler material and quality may be decided depending on the desired weight. In the preferred embodiment the U shaped circular shell member determining the desired outer peripheral shape adapted to fit into available interior space of the wheel.
As described and illustrated in the preferred embodiment, one shell has a interior volume and second shell is a flat surface. This means first ballast is fitted on the wheel, wherein the projected shell adapts to fit into the interior space of the wheel. For easy mounting the second ballast will be mounted end-to-end of two flat surfaces of first weight and second weight in the preferred embodiment.
The concrete filling core, may be of different quality with variable strength and water absorption capacity. However this hardly affects the performance of ballast, as it is safely enclosed within the polymer shell. Any damage to the core will also not affect the performance of ballast, as the broken pieces remain in position without any movement. The only precaution to be taken is that the concrete does not powder due to damage or deterioration.
The quality of the concrete as filler is decided considering a differential expansion between the polymer shell and concrete filler. The differential expansion is favorable, as the concrete filler will not expand beyond the expansion of polymer shell, thereby totally eliminating the fear of cracking of outer polymer shell.
The additional advantage is that the shell could be single member or made of 2 members to form annular ring shape.
The shell sections can be formed with desired shape and size with ensured quality.
Any differential expansion and contraction can occur without disturbing the core and cracking the shell.
The shell member can be easily made and transported and can be stocked and fitted onto vehicle with ease.
Further the polymer shell provides the basic resistance, and seals off the core filling materials, which means the shell can be filled with any ballast material, and said material need not necessarily be of high quality.
It is to be understood that the scope of concrete as filler material is not limited, as any equivalent material like sand, rubber, grovel, water, liquid may be filled, which may or may not adhere to the shell, but care to be taken for sealing when using the water or liquid as filler material.
As described earlier shell means are formed with spaced holes, which assist in filling the core within. The holes are formed by dummy caps or plugs placed in the shell mould or the holes are cut from the shell cast completely as one piece and the holes are cut by cutting equipment.
To seal, either caps can be separately molded or after core material has been filled to seal the opening with cast-in-place polymer concrete material or pure concrete mixture can be used to plug the holes.
Further according to the present invention, reinforcing material is not critical, but when used such reinforcing materials means are steel rods, steel mesh or glass fibre for example are placed in the mould. In the preferred embodiment three radially positioned steel rods are envisaged.
Securing means is also cast in the shell and in the core. An example is the hole in the end piece of shell and the rod structure embedded in the core filling material extending onto the end pieces, such that the shell is anchored strongly with the support of shell and core as illustrated in the drawing in figure 1. The ballast has a bolt means cast in the shell end piece and extending therefrom, which can be secured by plate, and bolt means to the wheel surface. A range of securing means may be adopted as this is not a critical feature for performance of ballast. Reference numerals if fig-1
2. Hollow case.
Another variant envisaged is that end piece need not be continuous along the periphery, but may be limited to small areas just sufficient for securing means.
Generally concrete and polymer do not adhere leading to the advantage that if differential expansion and construction of shell and core does occur, it will not crack the shell. Further the concrete filler is preferred, as there is no chance that this concrete fill, once formed, can be dislocated easily to leave any substantial space between it and the shell sides.
However as the fill is generally completely protected by outer polymer structure of the shell, the quality is not of prime importance, thereby reducing the raw material cost.
1. A concrete ballast comprising a relatively strong thick outer annular ring shaped shell integrally pre-formed defining an interior space within, filled with filler material and having an outer surface defining a desired outer shape of the ballast, and having spaced apart openings on the surface of the shell for receiving filler concrete material; alongwith means to secure the ballast to the wheel surface.
2. A concrete ballast as claimed in claim-1, wherein one shell member being adapted for end-to-end arrangement with another shell member to form an annular ring with interior space for receiving the filler material.
3. A concrete ballast as claimed in claim-1, wherein atleast one shell member comprises of U shaped cross section with the 3 legs terminals with each end, projecting out wards to form a circumferential projection.
4. A concrete ballast comprising:-
a hollow annular polymer shell defining an interior space within and with
openings on the surface of the shell,
an inner concrete core in the interior space consisting of filler material,
means sealing the openings in the shell members, and
means securing the ballast to the wheel disc.
5. A concrete ballast as claimed in claim-1 & 4, wherein the secure means comprises of spaced out fixing holes along the peripheral projected edge of the shell, for fitment of shell onto wheel disc.
6. A concrete ballast as claimed in claim-1 & 4, wherein separately fabricated reinforcing means of plurality of steel rods are radially fitted into the interior space and adapted to terminate at said fixing holes of the shell.
7. A concrete ballast as claimed in claim-1 & 4, wherein the each reinforcing steel rod at the distal end has a hole cooperating with the corresponding fixing hole on the peripheral projected edge of shell.
A concrete ballast as claimed in claim-1 & 4, wherein the inner core may be a cast-in-place type of concrete or may be filled with loose, wet concrete mixture, which is dried thereafter.
A concrete ballast as claimed in claim-1 & 4, wherein sealing the openings on shell member consist of separately preformed plugs or caps.
A concrete ballast as claimed in claim-1 & 4, wherein the polymer, concrete sealing the opening shell member consist of cast-in-place polymer concrete or pure cement mixture, the surface locally painted to the color of polymer shell.
|Indian Patent Application Number||1394/CHE/2006|
|PG Journal Number||18/2010|
|Date of Filing||04-Aug-2006|
|Name of Patentee||TRACTORS AND FARM EQUIPMENT LIMITED|
|Applicant Address||Having its Principal place of Business at Huzur Gardens, Sembiam, Chennai-600 011.|
|PCT International Classification Number||B62D37/00|
|PCT International Application Number||N/A|
|PCT International Filing date|