The invention relates to material developments and improvements over a variant known-to the Art of a distributor for hydraulic hoists used for positioning a plurality of attachments on agricultural use.
DESCRIPTION OF PRIOR ART
A distributor for hydraulic hoist is known to the Art. One such variant is the subject of Patent No. 197333 with effective date 16 November 1998 issued by the Patent Office, Government of India. The Art suffers from several disabilities that the present invention seeks to correct.
The Distributor of the Art cannot be used for the following applications over extended^ period of time without deterioration of efficiency and/ or cannot be used for continuous application for plurality of designated operations:
a. In PUDDLING operations
b. Continuous usage on dry land over extended time periods
c. ' For quick drop applications optimum lowering time
The present invention in its preferred embodiments addresses these disabilities and offers substantial improvements on these parameters over the ART.
SUMMARY OF THE PRESENT INVENTION
The present invention effectively cures the inherent defects and disabilities present in the ART while at the same time preserves the capabilities thereof but in an enhanced form. In one classical embodiment the Distributor in the ART is required to be used to operate PUDDLING operations. The process being such the operation leads to generation of high temperatures within the elements of, the Distributor, since the sealing of hydraulic medium is on the basis of metalto metal contact. Such generation of heat leads to the internal temperatures reaching such a level that the coefficient of expansion of the metal disrupts the precise tolerances that are required for the effective functioning of the device in an

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uninterrupted manner without loss of efficiency or at all. On this account the device cannot be used uninterruptedly over a long period of time in a PUDDLING or like operation. The loss in efficiency also leads to a reduced output as regards the operation itself, i.e. the agricultural operation being conducted by the Tractor. This is a very serious disability that is intrinsically an attribute of the Distributor as per prevalent ART. Another serious disability is the inefficient lowering time of the implement being used to conduct agricultural operations leading to lower productivity, output and efficiency of the fields under cultivation. Both these disabilities are largely addressed in the preferred embodiment of the present invention, leading to improved utilization, higher efficiency, better economy and higher output.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows in.a diagrammatic form the improvements effected in the Flow Control Valve (FCV) over the Art. It may also be noted that the diameter of the main spool has been increased from 4 mm to 6 mm.
Figure 1 (A) exhibits the improvement over the ART done to the Discharge Valve Assembly.
Figure 2 maps the temperature gradient comparison on continuous use over time of the ART with the present invention
Figure 3 shows the improvements in the cone angle of the existing valve as it is changed from the present 70 degrees to 90 degrees. This drastically improves the response/ lowering time constant.
Figure 4 graphically depicts Lowering Time Improvement.
Figure 4(A) exhibits in a chart form the improvements made as regards better lowering time constant, and the impact on the preferred embodiment of the present invention.
Figure 5 depicts additional two holes in the invention over four holes in the ART taking the total number of holes to 6 numbers in the preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
This disability is sought to be corrected by replacing the metal to metal contact (between the moving and fixed parts) basis of internal sealing of hydraulic medium with a metal to high temperature resistant (HNBR) contact, that not only allows a seamless operation of the device notwithstanding high internal temperatures, but also materially reduces the generation of heat on account of the fact that there is no metal to metal contact for sealing purposes. The present invention incorporates the introduction of an HNBR 0 Ring seal in places where sealing of the hydraulic medium is internally required in the device.

FIGURE 1 exhibits this development in the present invention.
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FIGURE 2 exhibits the characteristics of the device in relation to temperature
Another serious disability in the Distributor of the ART is the inability of the device to maneuver a quick descent of the agricultural implement attached to the Tractor. As a result thereof material tracts of land get untilled in places where the Tractor takes turns at the end of the portion of land being worked upon. Large tracts of land escape being worked upon by the Tractor and the implement being used, leading to an unwarranted loss of efficiency and productivity. This is on account of the fact that the internal mechanism in the Distributor of the ART is designed in a fashion that the time constant for response of a descent instruction of the control lever is high and by the time the agricultural implement descends and gets into contact with the land being worked upon, the Tractor has moved on and the land escapes the benefit of contact with the agricultural implement. This is an inherent disability built in the Distributor of the ART. The present invention in its preferred embodiment corrects this aspect by a reinvention of the profile of the internal valve element that controls the descent phase. FIGURE 3 exhibits this reinvention in the preferred embodiment of the present invention. As can be seen the changed profile of the valve ensures a reduced time constant in the descent phase of the device. FIGURE 4 demonstrates the graphical representation of time vs descent both in the Distributor of the ART and in the present invention in its preferred embodiment. In combination with the above 4 numbers holes in the ART have been changed to 6 numbers in the preferred embodiment of the present invention. The resultant efficiency improvement chart is shown in Figure 4(A).
Another serious disability in the Distributor of the ART is lack of control on the descent speed when a heavy load is attached to the three point linkage. This can cause serious issues as regards comfort of working the device in operation and material damage to the device/ implement. Introduction of an optional descent regulator phase allows the control valves to automatically adjust the lowering speed when a heavy load is attached to the three point linkage (Load Sensing Valve: LSV); FIGURE 5 demonstrates the LSV configuration in the preferred embodiment of the invention. This system also guarantees almost equivalent down stroke times with lighter loads. This collaterally ensures better comfort during the lowering of the implement and allows assembling the control valve on Chassis-cab Tractors where it is not possible to manually reach the controls normally found on standard control valves of the Art. The adjustment of the lowering speed can also be attained by manual intervention.

We Claim:

A Reinvented Distributor For Hydraulic Hoist With Material Improvements Over The Art
A'Distributor in Claim 1 in which the ability to be optimally used without loss of efficiency is higher in the preferred embodiment of the present invention over the ART
A distributor in Claim 1 that can be efficiently used continuously for in wet or dry conditions without the temperature of the device rising beyond acceptable levels
A Distributor in Claim 1 that has an improved time constant over that of the ART.
A Distributor in Claim 1 that has an automated descent improvement in time constant
A Distributor in Claim 1 that has a manually controlled descent speed improvement
A Distributor in Claim 1 that has an improvement in descent phase leading to improved productivity of the device
A Distributor in Claim 1 that has improved Hitch Regulation over the ART