1. A device for lifting and holding two parallel vehicle wheels off a floor comprising:
a first platform assembly and a second platform assembly, said first platform assembly and said second platform assembly each containing a flat plate, a front brace, a first side wall and a second side wall, wherein a rear portion of said first side wall comprises a notch and a rear portion of said second side wall comprises a notch, said flat plate having a uniform thickness;
a support bar disposed in parallel with the floor, said first platform assembly and second platform assembly being attached to the support bar in a manner that said first platform assembly and second platform assembly are being configured for horizontal and sideways sliding only movement on said support bar, said first platform assembly and second platform assembly also being configured for positioning and repositioning on said support bar;
said sideways sliding movement of the first platform assembly and the second platform assembly being configured to adjust a distance between the first platform assembly and the second platform to line up with vehicle wheels respectively,
said first platform assembly being adapted for containing only one vehicle wheel and said second platform assembly being adapted for containing only one vehicle wheel;
said flat plate being configured for lifting and holding a vehicle wheel, said flat plate also being configured for wedging between the wheel and the floor, said wedging being accomplished by using sufficient force on the device as to insert said flat plate between the wheel and the floor, said flat plate being configured only for movement parallel to the floor;
said notch being adapted to hold a barrier rod for preventing the wheel from shifting off the plate;
a hoist member for lifting the support bar upward and lowering said support bar to the floor; and
a power supply for the hoist member.
2. The device of claim 1, further comprising a stabilizing ballast for preventing the device from tipping off balance.
3. The device of claim 1 wherein the thickness of each flat plate ranges from about 0.1 inches to about 0.15 inches.
4. The device of claim 1 wherein a material of construction of each flat plate is steel.
5. A method of lifting and holding two parallel vehicle wheels using a device comprising:
a first platform assembly and a second platform assembly, said first platform assembly and said second platform assembly each containing a flat plate, a front brace, a first side wall and a second side wall, wherein a rear portion of said first side wall comprises a notch and a rear portion of said second side wall comprises a notch, said flat plate having a uniform thickness; a support bar disposed in parallel with the floor, said first platform assembly and second platform assembly being attached to the support bar in a manner that said first platform assembly and second platform assembly are being configured for horizontal and sideways sliding only movement on said support bar, said first platform assembly and second platform assembly also being configured for positioning and repositioning on said support bar; said first platform assembly being adapted for containing only one vehicle wheel and said second platform assembly being adapted for containing only one vehicle wheel; said flat plate being configured for lifting and holding a vehicle wheel, said flat plate also being configured for wedging between the wheel and the floor, said wedging being accomplished by using sufficient force on the device as to insert said flat plate between the wheel and the floor, said flat plate being configured only for movement parallel to the floor; said notch being adapted to hold a barrier rod for preventing the wheel from shifting off the plate; a hoist member for lifting the support bar upward and lowering said support bar to the floor; and a power supply for the hoist member;
said method comprising:
maneuvering said device in a manner that the rear portion of the side walls face the wheels to be lifted;
aligning each platform assembly in front of a corresponding wheel by moving said each platform horizontally on the support bar;
with the flat plates in parallel position with the floor, horizontally pushing the device toward the wheels in a manner such that each flat plate is wedged underneath its corresponding wheel and each wheel is contained within its corresponding flat plate;
placing each barrier rod in the respective notch on the rear end of the first side wall and second side wall of each platform assembly; and
activating the hoist to lift the platform assemblies along with the wheels to a desired height and holding the wheels at said height as needed.
6. The method of claim 5 further optionally comprising:
after pushing the device toward the wheels, activating the hoist to lift the wheels a short distance;
further pushing the device in such a manner as to enable each flat plate to further wedge under its corresponding wheel;
activating the hoist to lower the support bar to the floor; and
continuing alternating pushing the device, lifting the support bar with the hoist, pushing the device and lowering the support bar until each wheel is fully contained within its corresponding flat plate.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A switching power supply circuit comprising:
an insulating converter transformer including a primary winding and a secondary winding insulated from each other, said primary winding and said secondary winding being loosely coupled to each other;
a switching circuit including a switching device for performing switching operation on a current flowing into the primary winding of said insulating converter transformer at a fixed frequency;
a primary-side parallel resonant capacitor provided on a primary side of said insulating converter transformer for forming a primary-side parallel resonant circuit in conjunction with inductance of said converter transformer;
a secondary-side resonant capacitor provided on a secondary side of said insulating converter transformer for forming a secondary-side resonant circuit in conjunction with inductance of said converter transformer;
a rectifier circuit for rectifying an alternating voltage obtained on the secondary side of said insulating converter transformer;
an active clamp circuit provided on the secondary side of said insulating converter transformer for clamping the alternating voltage obtained on the secondary side of said insulating converter transformer in synchronism with the switching operation of said switching circuit; and
a constant-voltage control circuit for effecting control for constant voltage by controlling a clamping period of said active clamp circuit and controlling an onoff-period duty ratio of a rectifying device of said rectifier circuit according to a level of output voltage of said rectifier circuit.
2. A switching power supply circuit as claimed in claim 1, wherein said switching circuit forms a part of a self-excited voltage resonance type converter.
3. A switching power supply circuit as claimed in claim 1, wherein said secondary-side resonant circuit is a series resonant circuit.
4. A switching power supply circuit as claimed in claim 1, wherein said secondary-side resonant circuit is a parallel resonant circuit.
5. A switching power supply circuit as claimed in claim 1, wherein said secondary-side resonant circuit is a series resonant circuit, and said rectifier circuit is a voltage doubler rectifier circuit.