Abstract:
A motorized scissor jack is provided including upper and lower limit switches. The motor is connected with a drive assembly that extends and retracts the jack through a displacement screw. The motor has two speeds. The jack is connectable to a vehicular or standard alternating current power source. The upper and lower limit switches limit the extension and retraction of the jack to defined peak and bottom points. The jack is configured for operation in inclement weather.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to scissor type jacks and, more specifically, to motor driven scissor jacks for vehicular applications. 
     2. Description of the Prior Art 
     There are other scissor jack devices designed for lifting and lowering an automobile. Typical of these is U.S. Pat. No. 2,218,733 issued to Watts on Oct. 22, 1940. 
     Another patent was issued to Scott on Jun. 24, 1969 as U.S. Pat. No. 3,451,655. Yet another U.S. Pat. No. 3,997,143 was issued to Rose on Dec. 14, 1976 and still yet another was issued on Mar. 31, 1987 to Chang et al. as U.S. Pat. No. 4,653,727. 
     Another patent was issued to Pickles on Jun. 7, 1988 as U.S. Pat. No. 4,749,169. Yet another U.S. Pat. No. 4,872,230 was issued to Levine on Oct. 10, 1989. Another was issued to Wagnon on Jul. 24, 1990 as U.S. Pat. No. 4,943,034 and still yet another was issued on Feb. 4, 1992 to Lonon as U.S. Pat. No. 5,085,407. 
     Another patent was issued to Yoshida on Jan. 13, 1998 as U.S. Pat. No. 5,707,043. Yet another U.S. Pat. No. 6,029,950 was issued to Yeh on Feb. 29, 2000. Another was issued to Farmer on May 29, 2001 as U.S. Pat. No. 6,237,953 and still yet another was issued on Oct. 9, 2001 to Huang et al. as U.S. Pat. No. 6,299,138. 
     U.S. Pat. No. 2,218,733 
     Inventor: Roy T. Watts 
     Issued: Oct. 22, 1940 
     This invention relates to a jacking arrangement for automobiles whereby a lifting jack is secured on the lower part of the chassis of a vehicle. The jack has a scissors configuration with a motor positioned between scissor arm elements. The extension of the jack is limited by a switch handle which is configured for cutting off the current flow as the switch is closed by the action of a jack arm approximately reaching a maximum extension position. Simultaneously, a switch handle is depressed changing the polarity of the current flow through the motor thereby positioning the motor for the retraction of the jack. At the instant prior to the jack reaching a maximum retracted position, polarity switch handle is depressed again reversing the polarity of the motor. 
     U.S. Pat. No. 3,451,655 
     Inventor: Lawrence P. Scott 
     Issued: Jun. 24, 1969 
     The present invention is a vehicular scale jack positioned on a wheeled trailer with an electric motor drive arrangement for the operation of lifting and descending of the vehicle to its position for operation. The jack has gear configured for a high speed and a low speed of operation. Switches and are used to control the direction of movement of the jack. Releasing the switches during operation stops the jack in the present position. 
     U.S. Pat. No. 3,997,143 
     Inventor: Frank P. Rose 
     Issued: Dec. 14, 1976 
     In-place vehicle jack assemblies of the pivoted lever type configured for being permanently mounted at the front and rear of the vehicle frame structure are described. Each of the jack assemblies comprise a unitary device which is independently operable by an electrical motor, and independently selectively controlled at the jack or remotely from the control compartment of the vehicle, control circuits for the jacking assemblies are interlocked with the ignition system of the engine, so that the jacks are operable only when the ignition switch is in an off position. Solenoid actuated relays mounted to the motor housing control the direction of rotation of the motor. The threads of the screw are disengaged from the nut in the fully retracted position. The screw then reengages the nut for extension. 
     U.S. Pat. No. 4,653,727 
     Inventor: Shoei D. Chang et al. 
     Issued: Mar. 31, 1987 
     The invention relates to motor driven scissors jacks for automobiles driven by an electric power source from the cigarette lighting socket of any automobile. The scissors jack includes a DC motor driven through a deceleration gear box for rotating a screw rod clockwise or counter-clockwise for the raising of the frames of scissors jacks. The jack provides the ability for the automatic raising of vehicles as well as the higher raising and lower collapsing functions and a more powerful raising capability. The jack also includes one ultimate switch for peak and low bottom points. The power supply is automatically cut off when a lower raising rod pushes snapping rod of an ultimate switch. 
     U.S. Pat. No. 4,749,169 
     Inventor: Joseph Pickles 
     Issued: Jun. 7, 1988 
     A motorized user applied actuator for automobile and like jacks having rotatable operating members for raising and lowering the jack platform. The jack comprises a casing having a drive member detachably cooperable with the jack operating member, an electric motor, and a lightweight step-down transmission connecting the motor with the drive member. The transmission comprises a plurality of staged planetary assemblages which effect a great reduction in speed and advantageous conversion of power. In several illustrated embodiments of the invention one or more handles are attached to the motor casing to provide a convenient hand grip for the manual extension and retraction of the jack. In one embodiment the drive member of the actuator has back-to-back elements alternately engageable with the jack operating member to effect a reversal of the jack movement without reversing the motor. A handle includes start and stop buttons conveniently positioned for application by a user. 
     U.S. Pat. No. 4,872,230 
     Inventor: Anthony Levine 
     Issued: Oct. 10, 1989 
     A portable automatic automobile scissor jack is described including an electrically powered automobile tire nut remover. The jack is powered through a cigarette lighter type plug by the automobile battery, and has an outlet for powering of a tire nut remover or other equipment. In another embodiment, the nut remover, powered by the auto battery, drives the jack. 
     U.S. Pat. No. 4,943,034 
     Inventor: Gerald E. Wagnon 
     Issued: Jul. 24, 1990 
     An adapter for a jack is described having a threadable jack shaft and a support platform that rises or lowers when the threadable jack shaft turns. The adapter has a housing containing a drive motor that is coupled to a drive shaft. The adapter has an engagement bracket for releasing and engaging the adapter to the jack. Spring loaded bolts bias the engagement bracket against the face of the housing. To stop the jack a switch can be positioned in a neutral position. In addition, at a lower limit the engagement bracket is disconnected from the support-alignment bar to disengage the drive shaft from the threaded jack shaft. A jack and adapter in combination and a method for operating a jack having support aligning bars wherethrough a threadable jack shaft rotatably passes to raise or lower a support platform of the jack upon rotation. 
     U.S. Pat. No. 5,085,407 
     Inventor: Edward M. Lonon 
     Issued: Feb. 4, 1992 
     A motorized jack assemblage for vehicles in the form of a kit is described containing a motor and reduction gear linkage adapted to be energized from the cigarette lighter or other source of electrical power in the vehicle. The gear linkage is adapted to drive mechanical coupling means, which keys into and operates a screw type lift jack, which in one case is part of the standard equipment for the vehicle, and in another case is a jack with a specialized base which is part of the kit. A toggle switch is used to control the movement of the jack and includes a right, left, and neutral position. 
     U.S. Pat. No. 5,707,043 
     Inventor: Kazuhiko Yoshida 
     Issued: Jan. 13, 1998 
     A driving joint for jacks is described including a joint block secured to an output shaft of an electric driving unit. A U-shaped connection plate connected at its opposite ends to the joint block and provides an elongated connection hole in its front wall. The connection plate can be engaged within the U-shaped driven joint, and the elongated connection hole can be fitted to a connection plate of a T-shaped driven joint. With this arrangement, various types of jacks having different types of driven joints can be driven using the forward and reverse controls of a single electric tool. 
     U.S. Pat. No. 6,029,950 
     Inventor: Neng-Chen Yeh 
     Issued: Feb. 29, 2000 
     A scissor jack assembly is described having two lower arms each having an upper end portion and a lower end portion pivotally attached to a base. The two upper arms each have an upper end portion pivotally mounted to a support bracket and a lower end portion pivotally mounted to the upper end portion of one of the two respective lower arms. A drive shaft rotatingly extends through the connection of the lower end portion of one of the two respective upper arms and the upper end portion of one of the two respective lower arms. A drive device including a motor connected to a drive gear train rotates the drive shaft electrically. A drive nut is exposed for driving by a tool such as a socket for the manual rotation of the drive shaft. Thus, the jack assembly can be operated manually or electrically. 
     U.S. Pat. No. 6,237,953 
     Inventor: Dennis E. Farmer 
     Issued: May 29, 2001 
     An automatic jack and wheel change system having at least one inverted jack driven by an electric motor permanently attached to the vehicle. The system may employ a jack disposed between the front and rear wheel on each side of the vehicle, or it may be equipped with a jack at each of the four wheels. The system also includes a novel wheel and hub-axle assembly featuring a split axle whose length may be adjusted by operation of an electric motor. The hub has a plurality of arms extending from the hub in a star-shape, each arm having a finger at its free end. The system requires the user to be careful to only lift the vehicle enough to relieve the load from the wheels in order for the axle to be moved linearly. Both the motor for raising the jack and the motor for adjusting the length of the axle may be operated by remote control. 
     U.S. Pat. No. 6,299,138 
     Inventor: Chen-Ti Huang et al. 
     Issued: Oct. 9, 2001 
     A direct drive electromotive jack device for releasing a torsional force is described and comprises a jack with a driving screw rod, an electromotive motor arranged with a deceleration gearbox, a torsional force releasing means directly connected to a positioning plate, and a power supply directly switch operable by an operator. The torsional force releasing means serves to connect the electromotive motor with the jack. The torsional force releasing means comprises a positioning plate for fixing the electromotive motor; two or more than two symmetric arms of torsional force; a bearing for being passed through the electromotive motor; and a switch connected to the driving screw rod. When the rotary shaft of the electromotive motor rotates, the torsional force can be cancelled by the torsional force releasing means for preventing the jack from generating a strain or being tilt; moreover, by a switch of a power source to control the direction of the current flow, the jack can be lifted or descended. 
     While these automobile jacks may be suitable for the purposes for which they were designed, they would not be as suitable for the purposes of the present invention, as hereinafter described. The present invention, a motor driven scissor jacks for automobiles configured for application during inclement weather and/or at night is driven by the electric power source from the cigarette lighter socket or 12 volt socket of any automobile. A motor is configured to drive a displacement screw, clockwise, and counter clockwise in order to provide for the raising and lowering of the frame portion of the scissor jack. Upper and lower limit switches positioned in sealed housings are provided for peak to preclude damaging the motor or drive system during the raising and lowering operations of the scissor jack of the present invention. 
     SUMMARY OF THE PRESENT INVENTION 
     A primary object of the present invention is to provide a motorized scissor jack for automobiles that can be used during inclement weather. 
     Another object of the present invention is to provide a motorized scissor jack that is driven by the electric power source from the cigarette lighter socket or 12 volt socket of any automobile. 
     Yet another object of the present invention is to provide a motorized scissor jack that a motor is provided for the rotation of a displacement screw, clockwise and counter clockwise in order to provide for the raising and lowering of the frame portion of the scissor jack. 
     Still yet another object of the present invention is to provide a motorized scissor jack for automobiles that provides an upper limit switch positioned in a sealed housing that as the jack moves in an upward direction a driving element on one portion of the upper structure makes contact with a biased displacement element on the opposing portion of the upper structure driving a contact of the biased element into a contact of a fixed contact to complete the limiting circuit. 
     Another object of the present invention is to provide a motorized scissor jack for automobiles that provides a lower limit switch that as the jack moves in a downward direction the displacement screw comes in direct contact with a limit switch roller and drives a contact of a bias displacement element into a fixed contact to complete the limiting circuit. 
     Yet another object of the present invention is a two speed motor configured for providing a slow and a rapid lift capability. 
     Still, yet another object of the present invention is to provide a motor to turn a drive assembly that causes a displacement screw to turn in a rotation that either grabs or pushes the distal end of the displacement screw. 
     Additional objects of the present invention will appear as the description proceeds. 
     The present invention overcomes the shortcomings of the prior art by providing a motor driven scissor jacks for automobiles driven by the electric power source from the cigarette lighter socket or 12 volt socket of any automobile configured for use during inclement weather and/or at night. A motor is provided for the rotation of a displacement screw, clockwise and counter clockwise in order to provide for the raising and lowering of the frame portion of the scissor jack. An upper and lower limit switch are positioned in sealed housings and provide for peak and low bottom point electrical cut-offs in order to limit its raising and lowering operations of the scissor jack. 
     The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying drawing, which forms a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawing, like reference characters designate the same or similar parts throughout the several views. 
     The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     In order that the invention may be more fully understood, it will now be described, by way of example, with reference to the accompanying drawing in which: 
     FIG. 1 is a perspective side view of a motor driven scissors jack with limit switches being positioned for use with a vehicle constructed in accordance with the present disclosure; 
     FIG. 2 is a perspective side view of the jack of FIG. 1 constructed in accordance with the present disclosure; 
     FIG. 3 is a side view of the jack of FIG. 1 in a first position constructed in accordance with the present disclosure; 
     FIG. 4 is a side view of the jack of FIG. 1 in a second position constructed in accordance with the present disclosure; 
     FIG. 5 is a close-up of the side view of the jack of FIG. 3 constructed in accordance with the present disclosure; 
     FIG. 6 is a simplified wiring diagram of the jack of FIG. 1 constructed in accordance with the present disclosure; 
     FIG. 7 is a close-up view of a lower limit switch of the jack of FIG. 1 constructed in accordance with the present disclosure; and 
     FIG. 8 is a close-up view of an upper limit switch of the jack of FIG. 1 constructed in accordance with the present disclosure. 
    
    
     DESCRIPTION OF THE REFERENCED NUMERALS 
     Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views, the figures illustrate the present invention. With regard to the reference numerals used, the following numbering is used throughout the various drawing figures. 
       10  motor driven scissors jack with limit switches 
       20  lower structure 
       22  first member of lower structure 
       24  second member of lower structure 
       25  base plate 
       26  base plate adapter 
       27  teeth on base plate adapter 
       30  lower limit switch 
       32  fixed connector 
       34  biased connector 
       36  roller assembly positioned on bias connector 
       38  sealed housing for lower limit switch 
       40  upper structure 
       42  first member of upper structure 
       44  second member of upper structure 
       45  lifting block 
       50  upper limit switch 
       52  fixed connector 
       54  biased connector 
       56  receiving element 
       57  displacing element 
       58  sealed housing for upper limit switch 
       60  displacement screw 
       62  displacement screw distal end 
       64  displacement screw proximal end 
       80  drive system 
       82  electrical motor 
       84  connector adapted for a vehicle or vehicular connector 
       86  wire 
       88  light 
       90  drive assembly 
       91  bearing 
       92  support bracket 
       93  drive adapter 
       94  U-shaped bracket 
       95  pin 
       96  output shaft 
       98  gear assembly 
       100  switch assembly 
       102  on/off switch 
       104  light switch 
       105  switch assembly housing 
       106  switch for selecting the upward direction at a slow or fast speed 
       108  switch for selecting the downward direction at a slow or fast speed 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following discussion describes in detail preferred embodiments of the invention. This discussion should not be construed, however, as limiting the invention to those particular embodiments, practitioners skilled in the art will recognize numerous other embodiments as well. For definition of the complete scope of the invention, the reader is directed to appended claims. 
     Referring now in specific detail to the drawings in which like referenced numerals identify similar or identical elements throughout the several views, and initially to FIG. 1, a novel motor driven scissor jack with limit switches or jack  10  is shown. Jack  10  is adapted for use with vehicles and uses a battery from the vehicle as a source of power. In addition, jack  10  is configured for use during inclement or adverse weather conditions. 
     Referring now to FIGS. 2 and 5, jack  10  includes a lower structure  20 , an upper structure  40 , an adapter  50 , a displacement screw  60 , and a drive system  80 . Displacement screw  60  defines a longitudinal axis-X. An axis-Y is perpendicular to axis-X and is aligned with the upward and downward movement of jack  10 . An axis-Z is perpendicular to axes X and Y. 
     Lower structure  20  includes a base  25 , a first member  22 , and a second member  24 . Upper structure  40  includes a first member  42 , a second member  44 , and a lifting plate  45 . 
     Base  25  includes two flat legs and a pair of longitudinally aligned flanges. The legs are preferably configured for receiving a removably positioned base plate adapter  26  defining a larger supporting surface area and including teeth  27  positioned around the perimeter of plate  26  and configured for gripping into ice. The larger supporting surface area of base plate adapter  26  advantageously provides distributes the load borne by jack  10  over a greater surface area. Having a lower ground pressure can reduce the likelihood of jack  10  sinking excessively into soft soils or mud, for example. 
     One end of members  22  and  24  are rotatingly connected to base  25  by pins. The opposing end of member  22  is rotatingly connected with one end of member  42  and a first or distal nut block  12 . Similarly, the opposing end of member  24  is rotatingly connected with one end of member  44  and a second or proximal nut block  14  (see FIG.  5 ). The opposing ends of members  42  and  44  are rotatingly connected to lifting plate  45  by pins. Lifting plate  45  defines a channel parallel to the axis-Y and adapted for receiving a vehicle. Members  22 ,  24 ,  42 , and  44  have an elongate channel structure with the open side facing inward towards the other members. 
     Displacement screw  60  has a distal end  62  and a proximal end  64 . Distal end  62  extends along longitudinal axis-X through first nut  12  and proximal end  64  is connected with drive system  80 . Displacement screw  60  is rotatingly connected with first nut  12  and second nut  14  such that the rotation of displacement screw  60  about the longitudinal axis drives lower structure  20  and upper structure  40  between a first or minimum height position and a second maximum height position. 
     Drive system  80  is fixedly connected to second nut  14  and includes a motor  82  and a drive assembly  90 . Proximal end  64  rotates within bearings  91  and is fixedly connected with a bifurcated or U-shaped bracket  94 . U-shaped bracket  94  has a pin  95  positioned in the vicinity of the tips of its bifurcated legs through which a drive adapter  93  is positioned. Drive adapter  93  is connected by an output shaft or rod  96  with a gear assembly  98 . Gear assembly  98  includes gearing means, such as bevel gears, configured to turn the drive output of motor  82  ninety degrees and connect it with drive output shaft  96 . Gear assembly  98  is fixedly connected with a support bracket  92 . The combination of U-shaped bracket  94 , adapter  93 , and pin  95  is a flexible rotating connection between displacement screw  60  and the gear assembly  98 . 
     Motor  82  is a two speed electrical motor configured for lifting a load at a first speed and a second speed, wherein the second speed is faster than the first speed. Motor  82  is positioned parallel to axis-Z in order to minimize the length of jack  10  along longitudinal axis-X. Motor  82  is fixedly connected with support bracket  92  and gear assembly  98 . 
     It should also be pointed out that the length of drive system  80  relative to structures  20  and  40  in the FIGURES is not considered to be proportional, but is increased for purposes of clarification of the description of the structure of the differing elements. The size of drive system  80  is intended to be minimized for safety reasons in order to minimize the amount of exposure of jack  10  and user during operational employment. 
     A vehicular connector  84  is adapted for coupling with a source of power or power means, such as a 12 volt automotive battery using a cigarette lighter. It is understood that the methods of coupling as well as the standard for vehicular electrical systems will evolve in time and vehicular connector  84  is intended to encompass future changes in coupling as well as voltage. A wire  86  connects connector  84  to drive assembly  80 . Vehicular connector  84  can also include a standard outlet connector for residential or commercial sources of alternating current and a transformer that can be connected with vehicular connector  84 . This can advantageously accommodate using an alternate source of power when in a garage or driveway situation when it is not desired to drive jack  10  off the automobile battery. 
     Jack  10  can also include a directionally adjustable light  88  having an in-line switch positioned on upper structure  40  proximal to lifting plate  45  and is connected with switch system  100  (see FIG.  6 ). Adjustable light  88  is configured to provide critical lighting for aligning lifting plate  45  with the chassis of the vehicle at night or during inclement weather. In one preferred embodiment, light  88  is a separately battery powered removably positionable assembly. 
     As shown in FIGS. 3 and 7, jack is in a first position wherein the height of jack  10  in the direction of axis-Y is minimized and elongate members  22 ,  42 ,  24 , and  44  are extended in proximity with longitudinal axis-X. 
     A lower limit switch  30  is positioned, in this one preferred embodiment, on member  24  and is aligned for contact with displacement screw  60 . Limit switch  30  includes a fixedly positioned connector  32  and a biased connector  34 . Biased connector  34  includes a connector positioned on an inner side of connector  34  aligned with fixed connector  32 . A roller assembly  36 , including a bracket and a roller, is positioned on an outer side of connector  34  facing towards displacement screw  60 . The roller is rotatingly positioned on an axle and connected to the bracket. It is recognized, however, that lower limit switch  30  can be positioned on any of the members, for example, and at any point within lower structure  20 , upper structure  40 , or support bracket  92  that provides suitable direct contact with displacement screw  60 . 
     Roller  36  is suitably configured and dimensioned to engage displacement screw  60 . For example, roller  36  can have at least partially concave outer cylindrical surface or define a channel suitable for the positioning of at least a portion of displacement screw  60 . Roller  36  is configured to roll or spin about an axis parallel with the axis-Z. 
     A sealed flexible housing  38  is positioned around lower limit switch  30  with the bracket and roller assembly  36  extending there from. Sealed flexible housing  38  is configured to displace longitudinally with the displacement of roller assembly  36  and to not come in direct contact with displacement screw  60  while keeping out rain, dirt, snow, as well as any other potentially intrusive material that can disrupt the performance of switch  30 . 
     When connectors  32  and  34  of lower limit switch  30  are in direct contact, as a result of the displacement by displacement screw  60 , the electrical connection for retracting or lowering jack  10  is effectively disconnected between drive system  80  and the source of power (see FIG.  6 ). This defines the shortest displacement of jack  10  in the direction of axis-Y and the first position. 
     Referring now to FIGS. 4 and 8, jack  10  in a second position wherein the height of jack  10  in the direction of axis-Y is maximized and elongate members  22 ,  42 ,  24 , and  44  are extended in the general direction of axis-Y. 
     An upper limit switch  50  is positioned on members  42  and  44  and provides an upper limit on the extension of jack  10  in the direction of axis-Y. Upper limit switch  50  includes a fixed connector  52 , a biased connector  54 , a receiving element  56 , and a displacing element  57 . In this one preferred embodiment, fixed connector  52  and biased connector  54  are positioned on member  44  and displacing element  57  is positioned on member  42 . 
     Biased connector  54  includes a connector element aligned with fixed connector  52  on an inner side and receiving element  56  positioned on an outer side towards displacing element  57 . Biased connector  54  is biased to an open position. 
     A sealed flexible housing  58  is positioned around upper limit switch  50  with receiving element  56  extending there from. Sealed flexible housing  58  is configured in one preferred embodiment to displace with receiving element  56  and to not come in direct contact with displacing element  57  or member  42  while keeping out rain, dirt, snow, as well as any other potentially intrusive material that can disrupt the performance of switch  50 . In another preferred embodiment, sealed flexible housing  58  also encompasses all of the components of upper limit switch  50  including displacing element  57  and receiving element  56 . Upper limit switch  50  and lower limit switch  30  can also include protective and/or guiding flanges positioned to protect the moveable elements from being damaged and ensure their alignment. 
     Displacing element  57  is suitably positioned on member  42  such that when jack is positioned at its maximum desired displacement, receiving element  56  drives the connector element positioned on biased connector  54  into direct contact with connector  52 . The direct contact of connectors  54  and  52  provides an electrical coupling which effectively disconnects the electrical connection for raising jack  10  between drive system  80  and the source of power. This defines the maximum displacement of jack  10  in the direction of axis-Z and the second position. 
     As shown in FIGS. 4-6, motor  82  drives jack  10  between the first and second positions through switch assembly  100 . Switch assembly  100  includes a waterproof housing  105  on which is positioned an on/off switch  102  for powering jack  10 , light switch  104 , separate up and down directional switches  106  and  108 , respectively, which selectively power a slow or fast motor speed. Switch assembly  100  is positioned on the proximal end of jack  10 . 
     Switch assembly  100  is configured to simplify the operational use of jack  10  including switches for on/off or power to jack  10  using switch  102 , light  88  using switch  104 , and movement of jack  10  between first and second positions using motor  82  speeds for up/down directions of movement using switches  106  and  108 , respectively. A direction and speed of movement of jack  10  is thus selected simultaneously and activated only as long as the respective switch is held in the depressed position or until a limit switch is contacted. In one preferred embodiment, an interlock prevents the simultaneous activation of switches  106  and  108 . 
     In operation, as shown in FIGS. 2-8, the user first assess the ground surface in which the car is presently positioned to determine whether to use base plate adapter  26  to disperse the ground pressure of the load jack  10  will be lifting. Jack  10  is removed from storage, base plate adapter  26  is positioned on lower structure  20  as required, and jack  10  is positioned on the ground surface in the approximate position of use with the proximal end of jack  10  pointing out or away from the vehicle. This enables easy access to switch assembly  100  and enables lift plate  45  to be aligned with the underside of the vehicle. Jack  10  is connected with a power source such as a car cigarette lighter using wire  86  and connector  84 . 
     Power to jack  10  is turned on using switch  102 . Light  88  is powered on using switch  104  as required. Light  88  can be directionally adjusted to align lift plate  45  with a lift point on the vehicle. Jack  10  can be actuated from any position, but preferably jack  10  is initially in the first position wherein jack  10  has a reduced or minimal height in the direction of axis-Y. Jack  10  can then readily fit between the ground surface and vehicle. Jack  10  can be selectively raised to the second position or upper limit of travel position wherein limit switch  50  is engaged or the position wherein jack  10  is extended sufficiently in the direction of axis-Y to lift the vehicle the desired distance from the ground. When jack  10  is in the first position or lower limit of travel position, limit switch  30  is engaged to preclude attempting to reduce the height in the direction of the axis-Y less than the first position. 
     After the required maintenance is performed, the height of jack  10  is reduced in the direction of axis-Y from the second position to the first position. Jack  10  can then be turned off, removed from under the car, and then disconnected from the power source. Base plate adapter  26  is removed as required.