Abstract:
A toy liquid storage tank includes an exterior cylindrical tank having a central vertical guide pole and a horizontally disposed flat roof. A motor gear drive mechanism linked to a pair of oppositely disposed cam lift arms raise and lower the roof along the guide pole. Roller wheels at the ends of the cams engage the roof to provide a smooth motion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a toy liquid storage tank having an internal mechanism which raises and lowers the roof to simulate the filling and emptying of liquid into and out of the storage tank. The device may be utilized in conjunction with a toy liquid transfer facility loading platform for simulating the transfer of liquids from the tank through a hose nozzle into a toy railroad tanker car fuel receptacle. The liquid transfer facility is the subject of copending application Ser. No. 09/950,371. 
     2. Description of the Prior Art 
     Previous devices for simulating movement of accessories utilized with toy train apparatus include miniature electric motors which control mechanical actions of the accessories, such as shown in U.S. Pat. No. 5,816,887 to Rudell et al. 
     U.S. Pat. No. 4,458,440 to D&#39;Andrade et al. shows the use of a rotatable vertical screw type mechanism for raising and lowering an elevator platform carrying objects up and down within a vertical silo building connected to a toy barn. 
     U.S. Pat. No. Des. 195,041 to Genin et al. shows the external appearance of a water tower accessory for a toy railroad. 
     While these prior art devices show various mechanisms for simulating movement of toy train accessories, none of these concern a liquid storage tank having a roof raising and lowering mechanism which simulates the filling and emptying of liquid into and out of the storage tank. 
     SUMMARY OF THE INVENTION 
     It is therefore the primary object of the present invention to provide a novel mechanism for simulating the filling and emptying of a toy liquid storage tank. 
     It is another object of the invention to provide a unique mechanism for raising and lowering the roof of a toy liquid storage tank. 
     It is a further object of the invention to provide a motor-actuated gear drive and lift cam arm which control movement of the roof along a central vertical guide. 
     These objects are achieved with a unique structure including an exterior cylindrical tank shell having a central vertical guide and a horizontally disposed flat roof which rides up and down along the vertical guide. A motor and gear drive mechanism are linked to a pair of oppositely disposed lift cam arms which raise and lower the roof. Roller wheels at the ends of the cam arms engage the underside of the roof to provide a smooth motion. Other objects and advantages will become apparent from the following description in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of the toy liquid storage tank with the roof in a raised position. 
     FIG. 2 is a perspective view of the storage tank from the top showing the roof in a lowered position. 
     FIG. 3 is a schematic side view of the tank in partial cross section showing a portion of the mechanism for raising and lowering the roof. 
     FIG. 4 is a schematic plan view of the mechanisms for raising and lowering the roof. 
     FIG. 5 is a schematic side view of the tank in partial cross section showing the roof in a raised position. 
     FIG. 6 is a schematic side view of the tank in partial cross section showing the roof in a lowered position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 1, the toy liquid storage tank  10  includes a cylindrical tank shell  12  supported on a base  13 . The tank includes a floating roof  14  which moves vertically up and down within the tank to simulate the filling and emptying of liquid fuel stored within the tank. Pipelines  16  adjacent to the tank represent connections to fuel supply sources. Realistic associated external structures include a side spiral staircase  18 , a work platform  20  alongside and above the tank and a moveable ladder  22  pivotally connected to the platform. The lower end of the ladder is connected to roller wheels  23  which ride on a guide  25  on the roof so that the ladder moves up and down with the roof. The up position of the roof simulates a full tank. 
     As shown in FIG. 2, the roof  14  is in a lowered position along with the ladder simulating an empty tank. A centering pole  24  secured on base  13  aids in guiding the vertical movement of the roof to maintain a balanced level central position within the tank. A guard rail  26  encloses a circumferential skirt  28  around the upper end of the tank. 
     The operation of the roof raising and lowering mechanism is illustrated in FIGS. 3-6. An electric motor  30  mounted on base  13  is connected to an external source of power and control switch  31  and includes a pair of dual axle oppositely facing output shafts  32 ,  34  which rotate in the same direction. Each shaft is coupled to a first drive gear  36 ,  38 . An intermediate gear  40  is coupled between gear  36  and a first output drive gear  42 . Secured to output gear  42  is a crank lift roller pin  44  which rotates with gear  42 . A first lift cam arm  46  is pivotable about a support axle  48  secured to a support  50  at one end of the lift cam arm. A first pair of roller wheels  52  are secured at the other end of cam arm  46 . 
     Drive gear  38  on output shaft  34  on the opposite side of motor  30  is coupled to second output drive gear  54 . A second crank lift roller pin  56  is secured to and rotates with gear  54 . A second lift cam arm  58  is pivotable about a support axle  60  secured to support  62  at one end. A second pair of roller wheels  64  are secured at the other end of cam arm  58 . Roof  14  rests on the two pairs of roller wheels  52 ,  64  which engage the underside of roof  14 . 
     With the mechanism assumed to be in an initial starting position of an empty storage tank as shown in FIGS. 2,  3  and  6 , the roof  14  and lift cam arms  46 ,  58  are in a lowered position. When motor  30  is actuated by the power control switch, dual shafts  32 ,  34  and drive gears  36 ,  38  start rotating in a counter clockwise direction. Intermediate gear  40  then rotates clockwise to then cause output drive gear  42  to rotate counterclockwise. Crank lift pin  44  also moves counterclockwise and in turn drives lift cam arm  46  to rotate counterclockwise about support axle  48 . Roller wheels  52  at the other end of lift cam arm  46  are thus moved upwardly. 
     At the same time, the opposite shaft  34  and drive gear  38  are rotating counterclockwise to cause output drive gear  54  to rotate clockwise along with crank lift pin  56 . This causes lift cam arm  58  to pivot clockwise about support axle  60  with roller wheels at the other end also moving upwardly. Both pairs of roller wheels engage the underside of roof  14  to raise the roof to the upper position shown in FIGS. 1 and 5. The movements of the two lift cam arms and gear drives are synchronized so that the roof moves smoothly and evenly in the upward direction with the central guide pole  24  maintaining a level balanced position. The dimensions of the various components are also coordinated to provide predetermined angular and vertical movement limitations to attain the upper position for simulation of the fill tank. 
     In order to reverse the operation and direction to attain a simulation of an empty tank, the electric motor control switch is moved to an opposite position. The shafts and drive gears then rotate clockwise with intermediate gear  40  rotating counterclockwise, and output gear  42  crank lift pin  44  and lift can arm  46  rotating clockwise. Roller wheels  52  then move downwardly. The opposite output drive gear  54  then rotates counterclockwise with crank lift pin  56  and lift cam arm  58  pivoting counterclockwise and roller wheels  64  also moving downwardly along the roof  14  guided by central pole  24  until the lowest empty tank position is attained. Intermediate positions and various up and down movements of the roof may be obtained by control of the motor power switch. The components may be varied in size to suit individual toy railway requirements. As a typical example, the storage tank may be about ten inches in height and ten inches in diameter. 
     While only a single embodiment has been illustrated and described, other variations may be made in the particular configuration without departing from the scope of the invention as set forth in the appended claims.