Hand truck with a frame provided with a substantially vertical guide, two wheels which are situated near the bottom side of the guide and which are rotatable about a transverse shaft, a handle which is situated near the upper side of the guide, a lifting device comprising a lifting element which is
Hand truck with a frame provided with a substantially vertical guide, two wheels which are situated near the bottom side of the guide and which are rotatable about a transverse shaft, a handle which is situated near the upper side of the guide, a lifting device comprising a lifting element which is displaceable along the guide and a lifting drive which is connected to the lifting element for displacing the lifting element, a motor for driving the wheels and a brake cooperating with the wheels for blocking the rotation of the wheels, in which a control device is provided which can be operated via the handle for switching the lifting drive and the motor on and off, characterized in that, in a lower driving position of the lifting element, the brake is released and, when the lifting element is moved from the lower driving position to a lifting position, the brake is engaged, in which case the wheels can be driven via the motor at a positioning speed.
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1. A hand truck having a frame comprising: (a) a substantially vertical guide,(b) two wheels situated near a bottom of the guide and which are rotatable about a transverse shaft,(c) a handle situated near the upper side of the guide,(d) a lifting device comprising a lifting element displaceable alon
1. A hand truck having a frame comprising: (a) a substantially vertical guide,(b) two wheels situated near a bottom of the guide and which are rotatable about a transverse shaft,(c) a handle situated near the upper side of the guide,(d) a lifting device comprising a lifting element displaceable along the guide,(e) a lifting drive connected to the lifting element for displacing the lifting element,(f) a motor for driving the wheels,(g) a brake cooperating with the wheels for blocking rotation of the wheels, and(h) a control device operable via the handle for switching the lifting drive and the motor on and off,wherein lowering the lifting element to a lower driving position releases the brake, and raising the lifting element from the lower driving position to a lifting position engages the brake so that the wheels can be driven via the motor at a positioning speed. 2. The hand truck according to claim 1, in which the motor, in the driving position of the lifting element, can drive the wheels at a speed of movement which is higher than the positioning speed. 3. The hand truck according to claim 1, in which the brake comprises the motor and at least one rotatable roller connected to the motor and which rotatable roller engages with the outer circumference of at least one wheel, which roller is attached to a pivoting arm in order to move the roller between an engagement position in which the roller bears against the outer circumference of the at least one wheel and a release position in which the roller is at a distance from the outer circumference of the at least one wheel. 4. The hand truck according to claim 3, in which the roller is connected to a bottom side of a substantially vertical pivot arm, which is connected to the frame so as to be able to turn about a tilting axle which is arranged parallel to the transverse shaft with a pulling or pushing element being connected to the pivot arm on one side and to a higher position on the frame on the other side, in which, in an equilibrium position, a longitudinal direction of the pulling or pushing element extends through the tilting axle, in a braking position, which is located on one side of the equilibrium position, of the pulling or pushing element, the pulling or pushing element producing a moment on the pivot arm which pushes the roller against the wheel and in a driving position, which is located on the other side of the equilibrium position, of the pulling or pushing element, this pulling or pushing element produces a moment on the pivot arm which pushes the roller away from the wheel. 5. The hand truck according to claim 3, in which the lifting element comprises a first ram situated above a tilting axle and a second ram situated below the tilting axle, with a guide connected to the lifting element engaging with the first ram during an upward lifting movement in order to push the pivot arm beyond its equilibrium position to the braking position, and during a downward movement engages with the second ram in order to push the pivot arm beyond its equilibrium position to the driving position. 6. The hand truck according to claim 1, in which the roller is driven by the motor via a worm gear. 7. The hand truck according to claim 1, in which the handle comprises a lifting switch and a driving switch. 8. The hand truck according to claim 1, in which a foot bracket is provided near the bottom of the frame, at a back of the hand truck. 9. The hand truck according to claim 1, in which the lifting device can be displaced in the vertical direction up to a bottom lifting position, beyond the wheels. 10. The hand truck according to claim 9, in which the lifting device is driven, via a cylinder and a pulley and cable system, in both an upward lifting direction and a downward pushing direction. 11. The hand truck according to claim 10, in which the cylinder is connected to three lifting pulleys with a top pulley being fixedly attached to a top of the frame, a bottom pulley being fixedly attached to the bottom of the frame and a central pulley being fixedly attached to the frame between the top and bottom pulleys, wherein a single cable runs from an attachment point on the lifting element, via a first outer lifting pulley to the central pulley, to a second outer lifting pulley, via the lifting element to the bottom fixed pulley, and from there via the top fixed pulley, to the central lifting pulley to an upper attachment point.
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이 특허에 인용된 특허 (7)
Mann Larry D. (805 Walnut Rock Springs WY 82901), Hand truck.
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