This invention relates to a system for adjustment of rack and pinion type - ---- --- - - -- + -- - -- -- - - - - - - . -
steering gear box and a method of operation thereof. The invention is also
directed to a lock nut wrench.
BACKQROUNDIPRIOW ART
Rack and pinion type.steering gear box having a housing (1) that houses a yoke
plunger, which is required' to be located a.1: a distance from a Rack damper
screw (2) as shown in fig 1 .A lock nut (3) is placed next to the screw. When the
distance between "yoke plunger" and "Rack damper Screw" increases. with
usage, noise is created. Therefore the clearance is required to be adjusted by
I adjusting the Rack Damper screw to ensure proper pinion shaft rotation .
torque/ steering effort.
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To perform this operation following steps arc: :Followed:
1. Suspension frame sub-assembly as in. fig. 2 (sub-assembly consisting of
suspension frame, stabilizer bar, stee:l-ing gear and suspension arm) is to
be dismantled from the vehicle;
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i 2. Steering gear is dismantled from suspeilsion frame sub-assembly
3. Loosening of lock-nut of steering gear using a spanner while holding
rack-damper screw.
4. Tightening or loosening rack-damper:.screw so as to meet the specified
pinion shaft rotation torque.
5.' Tightening lock-nut of steering gea.r using a spanner while holding rackdamper-
screw .
6. Assembling steering gear to suspensiol:~fr, ame sub:assembly
7. Assembling suspension frame sub-assembly on to vehicle.
'!'he current method is challenging as it involves dismantl- in-- g- a- -n d as-se.mb ly ~f
suspension frame sub-assembly which nec:ds skilled manpower and is also
time consuming requiring around 3-4 hours per vehicle.
The aforesaid provision as in fig. 3 involves a cylindrical cup shaped screw (1)
with two slots (2) diametrically opposite is fitted into the housing of steering
gear box. The screw's movement is restricted by means of a lock nut (3), which
is square in shape as in the figure. However, it can have a hexagonal shape as
well.
However, it is associated with the following drawbacks:-
- Adjustment of the screw is done by its rotational movement through trial
and error. Therefore it is not accurate. and may require further
adjustment by di.smantling the whole set-up.
- Nut outer peripheral surface is square/hexagonal requiring a spanner
(tool) with closed head having a corresponding square/hexagotlal '.
peripheral surface for tight grip to rotate the spanner through an angle of
90: 180°/60- 120" respectively.
- The tool kit used for tightening/loosening screw and nut as in fig. 4 is i assembly of a plurality of parts, wh.ich is bulky and also expensive.
??,vex if the tool particularly meant for ;i~djustment of screw and nut is
considered, it is also bulky as shown in I'ig. 5 consisting of two cylindrical 1
members (1,2) telescopically provided w i1:h the closed, head (3) having I
square / hexagonal peripheral surface. TI- is renders the known system I
expensive. End cost is also high.
Another system for adjustment of the steering gear box is also available in the
market, according to which the rack damper screw is tightened inside the
housing. Here nut is not available.
The above involves punching on the housing for locking of the screw after
I tightening at the time of manufacturing Steering ear Box. However, following
1 adjustment of screw, the punching on housi.ng is not recommended, otherwise
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the housing may be damaged. This gives rise to chances of slipping out of the
screw from the assembly involving other drawbacks already discussed.
Furthcr reference may be made to a disclost.rre wherein marking is provided in
the form of engravings on "Rack damper Screw" to measure angle of rotation.
Hexagon head is provided on "Rack damper Screw'' for tool fitment. Engraved
"Rack damper Screw" is used without lock nut, therefore no positive locking is
ensured after setting yoke clearance.
In view of the above, there is a need to develop a system for adjustment of rack
and pinion type steering gear 'box and a lock nut wrench which can serve the . .
purpose for which the present invention has been devised.
QBJECTS OF THE INVENTION
Primary object of the present invention is to provide a system for adjustment of
rack and pinion type steering gear box and rnethod of operation thereof and a
lock nut wrench which overcomes disadvantages associated with the prior art.
Another object of the present invention is to provide a system for adjustment of
rack and pinion type steering gear box and method of operation thereof and a
lock nut. wrench which does not require dkmantling of Steering Gear Box fur
adjustment of rack damper screw to maintain required clearance from the yoke
plunger.
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Further object of the present invention is to provide a system for adjustment of
rack and pinion type steering gear box and method of operation thereof and a
lock nut wrench which is cost effective and rc;sults in low end cost.
Yet a.nofher object of the present invention is to provide a system for
adjustment o'f rack and pinion type steering gear box and method of operation
thereof and a lock nut wrench which requires a compact tool for
tightening/loosening of nut and screw.
SUMMARY OF THE INVENTION
According to this invention, there is provided a system for adjustment of rack
and pinion type steering gear box comprisil-~gsu spension frame sub assembly
,mounted with steering gear box having a ~.;lckd amper screw with a stepped
configuration and an octagon nut, which are adjusted by means of respective
tool.
Further according to t.his invention, there is provided a lock nut wrench
comprising a head and a tail with a handle therebetween constituting a single
structure wherein the head comprises a double decked flat structure with arc
shape, which isopen in one side.
Yet further according to this invention, there is provided method of operation of
system for adjustment of rack and pinion type steering gear box comprising
- insertion of the lock nut wrench through the slot in suspension frame for
removal of the lock nut of steering gear;
- tightening or ~~~~~~~~ng the rack-damper screw with the help of extension
rod/bar so as to adjust steering effort to specification; and
- tightening the nut using lock-nut wrench while holding the rack-damper
screw in position.
BEEF DESCRIPTION OF THE ACCOMPANYIN!; DRAWINGS
Further objects and advantages of this inveiltion will be more apparent from
the ensuing description when read in co~~junctiowni th the accompanying
drawings of exemplary embodiments of invention and wherein:
Fig. 1 shows: Steering gear box of prior art.
Fig. 2 shows: Conventional suspension frame sub assembly.
Fig. 3 shows: Rack-damper screw and l(:lck nut according to prior art.
-7. ri ig. 4. shows: Current tool kit.
Fig. 5 shows: ' Existing tool for adjustment of rack-damper screw and lock
nut.
Fig. 6 shows: Rack-damper screw of present invention.
Fig. 7 shows: Sectional view of fig. 6.
Fig. 8 shows: Tool for adjustment of rack-damper screw according to
present invention.
Fig. 9 shows: Octagon lock nut used in the present invention.
Fig. 10 shows: Suspension frame with a. comparatively smaller slot of the
invention.
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.ii lg. 1.1: shows: Lock nut wrench in accorc:lance with invention.
DETAIL DESCRIPTION OF THE INVENTIIIN WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
Thc invention discloses a system for adjustment of rack and pinion type
steering gear box. Said system comprises a specially designed rack damper
screw with aD octagon lock nut and a, corresponding compact tool for
tightening and loosening the' screw and nut.
Now reference may be made to fig. 6 indicating novel rack damper screw of the
. invention comprising a solid cylinder (1) wit11 a square slot (2) at the centre for
adjustment (tightening/loosening) of screw using a tool. The slot is preferably
but not necessarily square in shape. Thus other suitable quadrilateral shapes
with taper can also be adopted. Referring to fig. 7 the screw has a stepped
configuration due to presence of the slot (2) at the centre of inner surface (I)
and difference in height between the inne:t- surface (I) and outer peripheral
surface (0) as shown.
In addition to the above, there. is provision of multiple projected markings (M)
along the entire outer peripheral surface (0) of screw maintaining an angle of
for example 10" between any two markings.
! This gives indication regarding angle of rotation and is provided for accurate
adjustment of the screw while tightening/loosening.
The tool for adjustment of the screw constitutes a rod following the shape of
1
1 the slot. In this particular case it is square shaped rod as in fig. 8 (without
restricting scope of the invention to the same) which is quite compact as
:compared to the conventional tool employed for the same purpose.
The lock nut as shown in fig. 9 is preferaldy octagonal because the angle of
rotation of spanner to hold the nut becol-nes less as the number of sides
increases.
Octa.gon shaped nut is employed for smaller rotational movement in the order
of 22.5-45'. So that a smaller slot (T) can bt:: provided in the suspension frame
as in rig. 10 through which adjustment of n ~ lits carried out.
In order to loosen/tighten the lock nut a. lock-nut wrench (tool). has been
designed which will be described herein bebw with reference to fig. 11.
'i'he wrench forms a single structure having a head (1) and a tail (2) for fitment
of torque wrench to tighten nut with a ha.nd1.e (3) there between. The handle (3)
establishes connectivity between said head and tail integrated to each other.
The head of wrench comprises a'double decked flat structure' with arc shape
which is open in one side as best seen in the figure. The lower deck (Dl) is
mounted with upper deck (D2) wherein the lower deck is having a radius (R1)
smaller than the radius (R2) of upper dec.1~( D2). The lower deck (Dl), inner
surface of which is a smooth surface and the upper deck (D4, inner surface of
which is saw toothed. The saw toothed surlace with' multitude of saw teeth is
provided for angle of rotation in the range 01 22.5-45'.However, both the decks
share a common outer peripheral smooth surface (P).
'The tail (2) constitutes preferably a squart: flat member (in accordance with
standards followed in practice) with a ho:lc: (H) at the centre for fitment of
torque wrench. ,
The handle (3) is a longitudinal flat member covered by sleeve for avoiding
paint peel off of suspension frame while operating through slot of the
suspension frame. The sleeve can be made oCTOM.
Further, there is angular transition (E) from the handle to head of wrench to
facilitate insertion of tool through slot (T) of suspension frame from vehicle
underbody.
Xethod sf operation
.. Insertion of the lock nut wrench through the slot in suspension frame for
removal of the nut of steering gear.
- Tightening or loosening the rack-dam:l:~ers crew with the help of rod so as
to adjust steering effort to specificatiol-I..
- Tightening the nut using lock-nut wrench while holding the rack-damper
screw in position.
Advantageous Features
Steering gear rack-damper screw adjustment from vehicle underbody
without dismantling of any parts unlike prior art.
Saving of manpower.
Very less time consuming adjustment.
Highly cost effective.
Compact tool with less number of par1 s.
Smaller slot i'n the suspension frame.
Accurate adjustment of the screw while tightening/loosening.
Ensures positive locking after setting yoke clearance.
Provision to connect to torque wrench.
Prevention of slippage while tightening/loosening the nut.
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, whicll is further set forth under the
.co'ollowing claims: -
1. A system for adjustment of rack and pinion type steering gear box
comprising suspension frame sub assembly mounted with steering gear
box having a rack damper screw with a stepped configuration and an
octagon nut, which are adjusted' by me:ans of respective tool.
2. A system for adjustment of rack and pinion type steering gear box as
claimed in claim 1 wherein the suspension frame sub assembly
comprising a smaller slot for adjustment of the nut and screw
therethrough.
3. A system for adjustment of rack ant1 pinion type steering'gear box as
claimed in claim 1 or 2 wherein the rack damper screw comprising a
solid. cylinder with a qua.drilat.era1 ::;lot at the centre for adjustment I
(tightening/loosening) of the screw by :tneans of a tool. 1
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4. A system for adjustment of rack and pinion type steering gear box as
claimed in any of the preceding claims wherein the stepped configuration i
comprising an outer peripheral 'surfi:~ce placed at a level higher than
inner surface with the slot at the centre thereof, wherein the slot is
preferably square shaped.
5. A system for adjustment of rack antl. pinion type steering gear box as
claimed in any of the preceding cla..i.ms wherein the outer peripheral
surface is provided with multiple projected markings on the entire
surface thereof maintaining same angle between any two markings.
I 6. A system for adjustment of rack ancl. pinion type steering gear box as
~ claimed in any of the preceding claims wherein the tool for adjustment of
I ~ the screw constitutes a rod according to the shape of the slot.
7. A lock nut wrench comprising a head and a tail with a ;>handle
therebetween constituting a single structure wherein the head comprises
a double decked flat.structure with arc: shape, which is open in one side.
8. A lock nut wrench as claimed in claim 7 wherein said double decked
structure co.mprising a lower deck rnoc.~ntedw ith upper deck located .at a
radius more than the radius of the lower deck.
9. A lock nut wrench as claimed in any of the preceding claims wherein
inner peripheral surface of the lower cleck and upper deck is smooth and
sawtoothed respectively.
10. A lock nut wrench as claimed in any of the preceding claims
wherein the sawtoothed su.rf ace with multitude of saw teeth is provided
for angle of rotation in the range of 22.5-45".
11. A lock nut wrench as clairnecl in any of the preceding claims
wherein the tail constitutes preferably. a square flat member with a hole
at the centre for fitment of torque wrench.
12. A lock nut wrench as claimed in any of the preceding claims
wherein the handle is a longitudinal i3at member covered by sleeve and
an angular transition is provided from the handle to head so as to
facilitate.insertion of tool through said slot of suspension frame. :
13. Method of operation of system for adjustment of rack and pinion
type steering gear box comprising steps of :-
- insertion of the lock nut wrench through the slot in suspension frame for
.removal of the nut of steering gear;
- tightening or.loosening the rack-damper screw with the help of rod so as
to adjust steering effort to specification; and
- tightening the nut using lock-nut wrench while holding the rack-damper
screw in position.
14. A system for adjustment of rack and pinion type steering gear box
and method of operation thereof and a lock nut wrench claimed in any
of the preceding claims is associated with the advantageous features
such as herein described.