FORM 2
THE PATENT ACT 1970 (as amended)
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10 and Rule 13]
TITLE: “A SYSTEM AND METHOD FOR OPERATING HYDRAULIC POWER STEERING SYSTEM OF A VEHICLE”
Name and address of the Applicant:
TATA MOTORS LIMITED, an Indian company having its registered office at
Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra,
INDIA.
Nationality: Indian
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.
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TECHINCAL FIELD
Embodiments of the present disclosure relates to a hydraulic power steering system of a vehicle, more particularly embodiments relate to a system for operating the hydraulic power steering system of the vehicle when the engine is in off condition.
BACKGROUND OF DISCLOSURE
Presently, the vehicles are provided with center-closed hydraulic power steering system with a conventional mechanical drive-train for reducing the steering effort by the driver. The power steering system includes a hydraulic pump mechanically driven by engine, a steering gear box fluidly connected to the pump and the steering gear box connected to a driver operated steering wheel through steering column. In the power steering system, the pump is driven by engine, so in engine off condition pump does not get any feed from the engine and hence the power steering system will not work in engine off condition. Therefore, handling of steering in the engine off condition will become very difficult.
One way of operating the power steering system in engine off condition is by providing hydraulic accumulator. For example U.S. Patent Application No.11/999,884 describes the use of accumulator which stores the hydraulic fluid under pressure when the hydraulic pump is operating and releases the same to operate the power steering in engine off condition. In this example the accumulator can operate the hydraulic power steering system only when the pressurized hydraulic fluid is present in the accumulator. Hence, the usage accumulator to operate the power steering to tow the vehicle for long distance is not possible.
In light of forgoing discussion, it is necessary to develop a system which continuously operates the hydraulic power steering system of the vehicle when the engine is in off condition and the vehicle is moving to reduce the effort of driver to steer the vehicle.
STATEMENT OF THE DISCLOSURE
Accordingly, the present disclosure provides for a system to operate a hydraulic power steering system of a vehicle, when engine is in off condition and vehicle is moving, said
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system comprises, a reservoir for storing hydraulic fluid, a hydraulic pump fluidly connected to the reservoir and a power steering gear box for supplying the hydraulic fluid, a power take off unit for operating the hydraulic pump using an idler gear of a vehicle transmission, wherein said power take-off unit is coupled to the idler gear of a vehicle transmission to operate the hydraulic pump in engine off condition, an actuation mechanism coupled to the power take-off unit for engaging and disengaging the hydraulic pump with the power take-off unit, and also provides for a method of operating a hydraulic power steering system when engine is in off condition and vehicle is moving, said method comprising acts of, actuating an actuation mechanism to engage a hydraulic pump with a power take-off unit, wherein said power take-off unit receives rotation motion from the idler gear of the vehicle transmission when engine is in off condition and vehicle is moving, and operating a hydraulic pump which is fluidly connected to a reservoir and a power steering gear box by the power take-off unit for supplying the hydraulic fluid to a steering gear box to operate the hydraulic power steering system in engine off condition.
SUMMARY OF THE DISCLOSURE
The shortcomings of the prior art are overcome and additional advantages are provided through the provision of a system and method as claimed in the present disclosure.
Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
One embodiment of the present disclosure provides a system to operate a hydraulic power steering system of a vehicle, when engine is in off condition and vehicle is moving. The system comprises a reservoir for storing hydraulic fluid, a hydraulic pump fluidly connected to the reservoir and a power steering gear box for supplying the hydraulic fluid. A power take-off unit for operating the hydraulic pump using an idler gear of a vehicle transmission, wherein said power take-off unit is coupled to the idler gear of a vehicle transmission to operate the hydraulic pump in engine off condition. And
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an actuation mechanism coupled to the power take-off unit for engaging and disengaging the hydraulic pump with the power take-off unit.
In one embodiment of the present disclosure, at least one non-return valve is provided in a hydraulic fluid flow line connected between the hydraulic pump and the steering gear box to prevent flow of the hydraulic fluid from the steering gear box to the hydraulic pump.
In one embodiment of the present disclosure, a pressure regulator is provided in the hydraulic fluid flow line connected between the hydraulic pump and the steering gear box to regulate pressure of the hydraulic fluid.
In one embodiment of the present disclosure, the actuation mechanism is selected from at least one of pneumatic actuation mechanism or mechanical actuation mechanism.
Another embodiment of the present disclosure relates to a method of operating a hydraulic power steering system when engine is in off condition and vehicle is moving. The method follows steps of actuating an actuation mechanism to engage a hydraulic pump with a power take-off unit, wherein said power take-off unit receives rotation motion from the idler gear of the vehicle transmission when engine is in off condition and vehicle is moving. Then, operating a hydraulic pump which is fluidly connected to a reservoir and a power steering gear box by the power take-off unit for supplying the hydraulic fluid to a steering gear box to operate the hydraulic power steering system in engine off condition.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
OBJECTIVES OF THE DISCLOSURE
One object of the present disclosure is to provide a system which operates the hydraulic power steering system when engine is in off condition.
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One object of the present disclosure is to provide a system which utilizes a rotational motion of rear wheel to operate the hydraulic power steering system during towing condition.
One object of the present disclosure is to provide a system which operates the hydraulic power steering system when engine is in off condition which is simple in construction and easy to assemble.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
FIG. 1 illustrates a schematic view of hydraulic power steering system having a system to operate the hydraulic power steering system when engine is in off condition.
FIG. 2 illustrates a sectional view of a power take-off unit of the present disclosure.
FIG. 3 illustrates sectional view of steering gear box.
FIG. 4 illustrates working principle of the power steering control valve.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be
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better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
To overcome the drawbacks mentioned in the background, a system which continuously operates the hydraulic power steering system (100) of the vehicle when the engine is in off condition and the vehicle is moving to reduce the effort of driver to steer the vehicle is disclosed.
As an exemplary embodiment FIG. 1 illustrates a schematic view of hydraulic power steering system (100) having apparatus to operate the hydraulic power steering system (100) when engine is in off condition example towing. The system comprises following components but not limited to, a reservoir (101) for storing the hydraulic fluid. A hydraulic pump (102) fluidly connected between the reservoir (101) and a steering gear box (105) for supplying the hydraulic fluid to operate the power steering system (100). The hydraulic pump (102) is connected between the hydraulic reservoir (101) and the steering gear box (105) through hydraulic fluid flow lines (108 and 115). A power take off unit (103) is provided in the system to operate the hydraulic pump (102) for supplying oil to the power steering system (100) when the engine is in off condition. The power take-off unit (103) is coupled to an idler gear (109a) of a vehicle transmission (109) for driving the hydraulic pump (102). An actuation mechanism (104) is provided in the system to engage and disengage the hydraulic pump (102) from the power take off unit
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(103). The actuation mechanism (104) comprises a handle (104a) which can be operated by either pneumatically or mechanically to engage and disengage the hydraulic pump (102) from the power take-off unit (103).
The system further comprises a non-return valve (106) in a hydraulic fluid flow line (108) connected between the hydraulic pump (102) and the steering gear box (105) to prevent flow of the hydraulic fluid from the steering gear box (105) to the hydraulic pump (102). A pressure regulator (107) is provided in the hydraulic fluid flow line (108) to regulate pressure of the hydraulic fluid entering the steering gear box (105). An outlet of hydraulic fluid flow line (108) is connected to a power steering control valve (105a) of the steering gear box (105) to supply the hydraulic fluid to operate the hydraulic power steering system (100).
When the engine of the vehicle is in off condition and if the vehicle has to be moved from one place to the other place, the vehicle is either towed with the use of other vehicle or pushed by suitable means to move the vehicle from one place to other. In these conditions vehicle will be moved in neutral gear. Hence, the vehicle rear axle (117) gives drive to vehicle transmission (109) with the help of propeller shaft (110). The power take-off unit (103) which is coupled to idler gear (109a) of the vehicle transmission (109) to receives rotation motion from the idler gear (109a) to operate the hydraulic pump (102). In one aspect of the present disclosure, the power take-off unit (102) is a low ratio power take-off unit (102), such that system can get more feed than transmission which is getting from rear axle (117) during aforesaid conditions.
Engagement and disengagement of a shaft of the power take-off unit (103) which is operating the hydraulic pump (102) with the idler gear (109a) of the vehicle transmission (109) is done through handle (104a), the actuation mechanism (104) of the handle (104a) is done either mechanical or pneumatic mechanism depending on condition. In one aspect of the present disclosure, in the pneumatically actuation mechanism comprises a pneumatic cylinder (104b) mounted proximal to the handle (104a) to actuate the handle (104a), and a switch (104c) operable by a user to actuate the pneumatic cylinder (104d). In the pneumatically actuation mechanism, when driver press the electrical switch (104c),
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solenoid valve (104b) will open the port of pressurized system air and the pressurized system air will push the piston of pneumatic cylinder (104d), which will move the handle (104a) will to engage and disengage the shaft of the power take-off unit (103) with the transmission. In another aspect of the present disclosure in mechanical actuation mechanism the user can directly shift the handle (104a) with his own effort i.e. mechanically.
The hydraulic pump (102) coupled to the power take-off unit (103) pressurize the hydraulic fluid coming from hydraulic reservoir (101). A non return valve (106) and a pressure regulator (107) are also connected in hydraulic fluid line (108) by which hydraulic fluid will be supplied to steering gear box (105). The pressurized fluid after coming from pressure regulator (107) directly go inside of steering gear box (105) through power steering control valve (105a). Operation of power steering control valve (105a) is proportionally controlled through the rotation of steering wheel (111). FIG. 3 shows the power steering control valve (105a) is further fluidity connected with steering gear box (105) through input (105b) and return groove (105c) to pass the hydraulic fluid to either one of connecting bores (105f and 105g) to assists the axial movement of the piston (105h) to rotate wheels either to left or right. The axial movement of piston (105h) converts the rotary movement of sector shaft (114) through worm gear (105i). Then the drop arm (113) mounted on the sector shaft (114) moves the steering linkage which goes to steering arms thus causing the road wheels to be turned.
When the steering wheel (111) is released or in case vehicle is moving in straight ahead condition, then steering wheel (111) doesn’t activate the power steering control valve (105a) and pressure difference between the pistons (105f and 105g) of the power cylinder chamber will be zero, thus flow of pressurized fluid will be bypass the power steering system. This high pressurized fluid will be return to reservoir (101) through return hydraulic fluid pipe line (105c) from steering gear box (105).
FIG. 2 is an exemplary embodiment which illustrates a sectional view of a power take off unit (103) of the present disclosure. The teeth of gear (103a) which is mounted on shaft of the power take-off unit (103) are meshed with teeth of idler gear (109a) of the vehicle
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transmission (109) so drive coming from the idler gear (109a) of vehicle transmission (109) always rotate the gear (103a). The gear (103a) will rotate the gear (103b) which is mounted on main shaft (103d) of the power take-off unit (103). When the handle (104a) of the power take-off unit (103) is actuated the shifter fork (103e) mounted on gear (103c) will move the gear (103c) to engage the gear (103c) with the gear (103b). The gear (103c) will be mounted on shaft coupled to the hydraulic pump (102), hence upon engagement of the gear (103c) with the gear (103b) will drive the hydraulic pump (102). The hydraulic pump (102) pressurize the hydraulic fluid coming from hydraulic reservoir (101) to pump (102) through hydraulic fluid line (115), then high pressurized fluid circulates to steering gear box (105) via non return valve (106) and pressure regulator (107). Here non return valve (106) is used to restrict the dual direction movement of hydraulic fluid while pressure regulator (107) is used for maintaining the pressure of hydraulic fluid flowing through the hydraulic fluid flow line (108). For deactivation of power take-off unit (103), driver will move the handle (104) mechanically or pneumatically to disengage the gear (103c) from the gear (103b).
FIG. 3 is an exemplary embodiment which illustrates a sectional view of steering gear box (105). The pressurized fluid coming from hydraulic fluid flow line (108) via pressure regulator (107) directly go inside of steering gear box (105) through power steering control valve (105a) when the steering wheel (111) is rotated by the driver in clock-wise or anti-clock wise direction. The power steering control valve (105a) is further fluidly connected with steering gear box (105) through input (105b) and return groove (105c) to pass the hydraulic fluid to either one of connecting bores (105f and 105g) to assists the axial movement of the piston (105h) to rotate wheels either to left or right. The axial movement of piston (105h) converts the rotary movement of sector shaft (114) through worm gear (105i). Then the drop arm (113) mounted on the sector shaft (114) moves the steering linkage which goes to steering arms thus causing the road wheels to be turned.
FIG. 4 is an exemplary embodiment which illustrates working principle of the power steering control valve (105a). Operation of power steering control valve (105a) is proportionally controlled through the rotation of steering wheel (111). If a torque is transmitted to the power steering control valve (105a) or the worm gear (105i) from the
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steering wheel (111), a relative rotary motion influenced by the torsion bar (112) will occur between the power steering control valve (105a) and the worm gear (105i). The power steering control valve (105a) is thereby caused to change its position in relation to the worm gear (105i), so that the relative position of the control grooves (105j), (105k), (105m) and (105n) are changed. Pressurized oil can now flow through connecting radial incoming groove (105e) to one of the two power cylinder chambers (105f) and (105g), to assist the axial movement of piston (105h). At the same time the sector shaft (114), which is arranged at right angles to the longitudinal axis of the piston (105h), is caused to rotate. Thus drop arm (113) mounted on the sector shaft (114) moves the steering linkage which goes to steering arm and causing to front road wheels to be turned.
When the steering wheel (111) is released i.e. no power steering required and vehicle is moving in straight ahead condition, the action of the twisted torsion bar (112) makes the power steering control valve (105a) grooves return to the neutral position, in this condition the same system pressure will exist in both of the power cylinder bores (105f and105g). Since in this case there will be no any difference in pressure between power cylinders bores (105f and105g) so movement of piston (105h) will be not exist and pressurized oil will be by pass through radial return groove (105d) to hydraulic reservoir (101) via return hydraulic fluid flow line (116).
Advantages:
The present disclosure provides a hydraulic power steering system of a vehicle which has a system to operate hydraulic power steering system in engine-off condition, hence steering effort of the driver is reduced during vehicle towing condition.
The present disclosure provides a hydraulic power steering system of a vehicle which has a system to operate hydraulic power steering system in engine-off condition which utilizes a rational motion of rear wheel to operate the hydraulic power steering system during towing condition.
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The present disclosure provides a system which operates the hydraulic power steering system when engine is in off condition which is simple in construction and easy to assemble.
Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a
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convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
Referral Numerals:

Reference number Description
100 Hydraulic power steering system
101 Reservoir
102 Hydraulic pump
103 Power take-off unit
103a, 103b and 103c Gears in the power take off unit
103d Main shaft of power take off unit
103e Shifter fork
104 Actuation mechanism
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104a Handle
104b Solenoid Valve
104c Switch
104d pneumatic cylinder
105 Steering gear box
105a Power steering control valve
105b Hydraulic fluid input port
105c Hydraulic fluid output port
105d Return groove
105e Incoming groove
105f and 105g Cylinder bores
105h Axial piston
105i Worm gear
105j, 105k , 105m and 105n Grooves in the steering gear box
106 Non return valve
107 Pressure transducer
108 Hydraulic fluid flow line connected
between hydraulic pump and steering
gear box
109 Vehicle Transmission
109a Idler gear of vehicle transmission
110 Propeller shaft
111 Steering wheel
112 Torsion bar
113 Drop arm
114 Sector shaft
115 Hydraulic fluid flow line connected between hydraulic pump and reservoir
116 Hydraulic fluid flow line connected between steering gear box and
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reservoir
117 Rear wheel axle
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We claim:
1. A system to operate a hydraulic power steering system (100) of a vehicle, when
engine is in off condition and vehicle is moving, said system comprises:
A reservoir (101) for storing hydraulic fluid;
A hydraulic pump (102) fluidly connected to the reservoir (101) and a power steering gear box (105) for supplying the hydraulic fluid;
A power take off unit (103) for operating the hydraulic pump (102) using an idler gear (109a) of a vehicle transmission (109), wherein said power take-off unit (103) is coupled to the idler gear (109a) of a vehicle transmission (109) to operate the hydraulic pump (102) in engine off condition; and
An actuation mechanism (104) coupled to the power take-off unit (103) for engaging and disengaging the hydraulic pump (102) with the power take-off unit (103).
2. The system as claimed in claim 1, wherein at least one non-return valve (106) is provided in a hydraulic fluid flow line (108) connected between the hydraulic pump (102) and the steering gear box (105) to prevent flow of the hydraulic fluid from the steering gear box (105) to the hydraulic pump (102).
3. The system as claimed in claim 1, wherein a pressure regulator (107) is provided in the hydraulic fluid flow line (108) connected between the hydraulic pump (102) and the steering gear box (105) to regulate pressure of the hydraulic fluid.
4. The system as claimed in claim 1, wherein the actuation mechanism (104) is selected from at least one of pneumatic actuation mechanism or mechanical actuation mechanism.
5. A method of operating a hydraulic power steering system (100) when engine is in off condition and vehicle is moving, said method comprising acts of:
actuating an actuation mechanism (104) to engage a hydraulic pump (102) with a power take-off unit (103), wherein said power take-off unit (103) receives
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rotation motion from the idler gear (109a) of the vehicle transmission (109) when engine is in off condition and vehicle is moving; and
Operating a hydraulic pump (102) which is fluidly connected to a reservoir (101) and a power steering gear box (105) by the power take-off unit (103) for supplying the hydraulic fluid to a steering gear box (105) to operate the hydraulic power steering system in engine off condition.
6. The method as claimed in claim 5, wherein preventing a flow of the hydraulic fluid from a steering gear box (105) to a reservoir (101) in a hydraulic fluid flow line (108) connected between the hydraulic pump (102) and the steering gear box (105) is by a non-return valve (106).
7. The method as claimed in claim 5, wherein regulating pressure of the hydraulic fluid in the hydraulic fluid flow line (108) connected between the hydraulic pump (102) and the steering gear box (105) is regulated by a pressure regulator (107).
8. A vehicle comprising a system to operate a hydraulic power steering system when engine is in off condition and vehicle is moving as claimed in claim 1.
9. A system and method to operate a hydraulic power steering system when engine is in off condition and vehicle is moving is as herein described accompanying drawings.
Dated this 13th Day of January, 2012. GOPINATH A.S.
IN/PA 1852
OF K&S PARTNERS
AGENT FOR THE APPLICANT
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“A SYSTEM AND METHOD FOR OPERATING HYDRAULIC POWER STEERING SYSTEM OF A VEHICLE”
ABSTRACT
The present disclosure provides a system to operate a hydraulic power steering system (100) of a vehicle, when engine is in off condition and vehicle is moving. The system comprises a reservoir (101) for storing hydraulic fluid and a hydraulic pump (102) fluidly connected to the reservoir (101) and a power steering gear box (105) for supplying the hydraulic fluid. A power take off unit (103) for operating the hydraulic pump (102) using an idler gear (109a) of a vehicle transmission (109), wherein said power take-off unit (103) is coupled to the idler gear (109a) of a vehicle transmission (109) to operate the hydraulic pump (102) in engine off condition. And an actuation mechanism (104) coupled to the power take-off unit (103) for engaging and disengaging the hydraulic pump (102) with the power take-off unit (103).
FIG. 1
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