FIELD OF INVENTION
This invention relates to an improved rockshaft and ram arm arrangement of hydraulic lift assembly.
PRIOR ART
The rockshaft and ram arm arrangement of a tractor's hydraulic lift is an important part of the hydraulic lift and comprises of Ram arm, Rock Shaft, Bushings supporting the Rock Shaft, Sealing Rings and Thrust Washer. It is required to perform the following functions:
To transfer force & linear movement generated by the Hydraulic Lift Cylinder of the tractor (via Ram Arm to Rockshaft) and convert it into angular rotation 8B Torque.
To enable management of implements with the help of 3 point linkage. Implements mounted at the rear end of the tractor can be raised or lowered in line with demand from tractor operator or from draft sensing system.
To ensure proper disposition of various parts along the Rockshaft axis and ensure desired plays between rotating & stationary parts. This is to ensure unrestricted & smooth movement of Ram Arm inside the Hydraulic Lift Cover & Lift Arms mounted on the Rockshaft outside the Hydraulic Lift casing.
Due to requirement of easy assembly clearance, bore at the end part of the Ram Arm hub is required to be bigger in size. Further, for axial retention, this portion needs to be extended till Bush and the extension

becomes non-load carrying part of the Ram Arm. This results in larger size and hence lesser operating clearances around it. There have been cases of Ram Arm fouling with the Hydraulic Lift Cover due to Unidirectional stacking of tolerance of various parts involved in the arrangement.
Reference may be made to fig. 1, 2, 85 4 representing details of the known Rockshaft arrangement. As shown in Fig. 1, Hydraulic Lift 1 carries Hydraulic Cylinder 3 and Cavity behind the Piston 4, when filled with pressure oil, pushes the Piston 4. Connecting rod 6 is connected to piston through spherical bearing area on Piston and transfers the movement & thrust to Ram Arm 7. Connecting rod 6 & Ram arm 7 are printed together to ensure rotational movement without binding. Further, Ram Arm 7 is in connection with Rockshaft 8 through Splines (Fig. 2).
Referring to Fig. 2, Rockshaft 8 is supported on Cover of Hydraulic Lift 1 and on pair of Bushes (9 85 10) on both the sides. On one side, thrust washer 11 is provided to absorb axial thrusts getting imposed during operation of the Hydraulic Lift.
Fig. 4 shows front & side view of the conventional Ram arm. The Ram Arm consists of two parts i.e. Hub 14 and Lever 15. Hub contains Splined portion 14 in the center 65 plain portion on the ends. One end of Hub 14 carries Position control Cam 16 & the other end carries plain portion. OD of the plain end 18 of the Ram arm moves in constrained area of cover 85 may have drawbacks of fouling due to tolerance stacking in various parts

involved in the area. Lever 15 carries strengthening ribs 20 so as to withstand the load imposed during force & motion transfer from Connecting Rod 6.
OBJECTS OF THE INVENTION
An object of the present invention is to propose an improved rockshaft and ram arm arrangement of hydraulic lift assembly, which overcomes the disadvantages associated with prior art.
Another object of the present invention is to propose an improved rockshaft and ram arm arrangement of hydraulic lift assembly, which leads to reduced weight and low cost benefit.
Further object of the present invention is to propose an improved rockshaft and ram arm arrangement of hydraulic lift assembly, which improves the operating clearance in the fouling prone assembly area.
STATEMENT OF INVENTION
According to this invention, there is provided an improved rockshaft and ram arm arrangement of hydraulic lift assembly comprising of modified ram arm having shorter width, a compact dimension spacer for axial retention, a modified hub and modified ribs of the lever.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig. 1 shows arrangement of elements for transfer of linear movement of
the hydraulic lift cylinder piston to the ram arm and a vertical section
through the Lift cylinder.
Fig. 2 shows the existing Rockshaft arrangement A horizontal section
through the Rockshaft.
Fig. 3 shows the Rockshaft arrangement according to the present
invention.
Fig. 4 shows existing Ram Arm.
Fig. 5 shows the Ram Arm according to the present invention.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The present invention discloses an improved rockshaft and ram arm arrangement of hydraulic lift assembly comprising of modified ram arm having shorter width, a compact dimension spacer for axial retention, a modified hub and modified ribs of the lever.
Fig. 3 indicating a schematic view showing the arrangement of parts in accordance with the present invention wherein modified Ram Arm 13 is used

which has shorter width. For axial retention, a compact dimension Spacer 25 is used. Since the Spacer 25 is of compact dimensions, more operating clearance is available around it. This eliminates fitment problem.
Reference may be made to fig. 5, in which the hub (21) is modified by trimming non-load carrying length of Plain part (24). Ribs (19) of the Lever (15) are modified by introducing special profile (22). This also results in lighter weight due to removal of some material (13). Further, profile is designed to ensure the stresses during use of loading are within safe limits. Again, on end of Hub (21), Chamfer (25) is introduced. This also results in lighter weight due to removal of some material (26).
Advantages
1. Better space availability at the Ram lever end- in high capacity Lifts, there have been cases of fouling/low operation clearance.
2. Cost effectiveness due to reduced weight of the ram arm forging resulting from modifications of profile.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

WE CLAIM:
1. An improved rockshaft and ram arm arrangement of hydraulic lift assembly comprising of modified ram arm having shorter width, a compact dimension spacer for axial retention, a modified hub and modified ribs of the lever.
2. An improved rockshaft and ram arm arrangement as claimed in claim 1, wherein the hub is modified by trimming non-load carrying length of Plain part.
3. An improved rockshaft and ram arm arrangement as claimed in claim 1 or 2, wherein ribs of the Lever are modified by introducing special profile.
4. An improved rockshaft and ram arm arrangement as claimed in any of the preceding claims, wherein the profile is designed in such a way that, stresses during use of loading are within safe limits.
5. An improved rockshaft and ram arm arrangement as claimed in any of the preceding claims, wherein one end of the hub is provided with chamfer.
6. An improved rockshaft and ram arm arrangement of hydraulic lift assembly substantially as herein described with reference to the accompanying drawings.