US3907138A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power control hand truck
Assignee: HAZEN ELMER
•
Filing: 1973-07-02
•
Granted: 1975-09-23
•
Expires: 1993-07-02
Abstract
Abstract An electrically powered, two wheeled hand truck having telescoping frame parts, the inner frame part being raised and lowered by electric power means in the form of a rotatable screw shaft which engages a bearing nut fixed to the inner movable frame part. Rotation of the screw in a particular direction either lowers or raises the inner frame part. A DC motor is carried by the hand truck and powered by a battery voltage source also carried by the hand truck. Electrical switching means select the direction of rotation of the screw shaft for lowering or raising the inner movable frame part. Rapid and accurately controlled raising and lowering allows moving a load carried on the movable frame part from a raised position to a lowered position and vice-versa. A braking means holds the screw shaft when the motor is turned off so that the load does not slip. Starting the motor overrides the braking means to either raise or lower the load.
Inventors
- 👤 Chester E Rhodes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:37
CPC Classifications
B; B62; B62B; B62B1/00; B62B1/10; B62B1/14; B62B5/00; B62B5/02; B62B5/023; B62B2202/00; B62B2202/02
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
254 words
A two wheeled hand truck assembly powered by a mounted electric motor for rapid and accurately controlled lowering and raising of a load, said hand truck having telescoping frame parts, and bearing means interconnecting said frame parts, the improvements which include: the electric motor mounted at one end of a stationary frame part, lead means connecting said electric motor to a voltage source, an elongated screw shaft rotatably connected to said electric motor at one end of said stationary frame part, the opposite end of said screw shaft being freely rotatable in a bearing mounted at an opposite end of said stationary frame part, a bearing nut mounted to a movable frame part intermediate the opposite ends of said screw shaft, said screw shaft engaging said bearing nut so that rotation of the screw shaft in a selected rotational direction either raises or lowers the frame part to which the bearing nut is mounted, switch means to selectively actuate said electric motor to rotate said screw shaft in either rotational direction, and brake means to prevent the shaft from rotating under carried loads when said motor is deactuated, said brake means having a member mounted to said shaft and a frame part member engagable at all times with said shaft mounted member when said hand truck is operative, said frame part engaging said shaft mounted member with sufficient friction to prevent rotation of the screw shaft under carried loads but with insufficient friction to prevent override from the torque of the actuated electric motor.
Claim 2
Dependent Claim
254 words
A two wheeled hand truck assembly powered by a mounted electric motor for rapid and accurately controlled lowering and raising of a load, said hand truck having telescoping frame parts, and bearing means interconnecting said frame parts, the improvements which include: the electric motor mounted at one end of a stationary frame part, lead means connecting said electric motor to a voltage source, an elongated screw shaft rotatably connected to said electric motor at one end of said stationary frame part, the opposite end of said screw shaft being freely rotatable in a bearing mounted at an opposite end of said stationary frame part, a bearing nut mounted to a movable frame part intermediate the opposite ends of said screw shaft, said screw shaft engaging said bearing nut so that rotation of the screw shaft in a selected rotational direction either raises or lowers the frame part to which the bearing nut is mounted, switch means to selectively actuate said electric motor to rotate said screw shaft in either rotational direction, and brake means to prevent the shaft from rotating under carried loads when said motor is deactuated, said brake means having a member mounted to said shaft and a frame part member engagable at all times with said shaft mounted member when said hand truck is operative, said frame part engaging said shaft mounted member with sufficient friction to prevent rotation of the screw shaft under carried loads but with insufficient friction to prevent override from the torque of the actuated electric motor.
Claim 3
Dependent Claim
33 words
A wheeled hand truck assembly which includes the features of claim 1 above wherein said member mounted to said shaft includes a brake drum and said frame part member includes a brake shoe.
Claim 4
Dependent Claim
39 words
A wheeled hand truck assembly which includes the features of claim 2 above wherein said frictional contact of the brake shoe with the brake drum is manually adjusted to vary the frictional contact for carried loads of different quantities.
Claim 5
Dependent Claim
75 words
A wheeled hand truck assembly which includes the features of claim 3 above wherein said brake show includes a flexible strap folded around the drum, the opposite ends of said strap B pivotally connected to a toggle linkage, and manual means to vary the position of the toggle linkage at the pivotal connections to vary the distance between the ends of the straps and thereby vary the frictional contact of the strap with the drum.
Claim 6
Dependent Claim
41 words
A wheel hand truck assembly which includes the features of claim 1 and which further includes a battery voltage source mounted to the stationary frame part, and said leads from said battery voltage source being connected to a DC electric motor.
Claim 7
Dependent Claim
70 words
A wheeled hand truck assembly which includes the features of claim 1 above and which further includes a U-shaped hook bar pivotally connected at the ends of its upright arms to the stationary frame part, said hook bar being movable from a raised inactive position to a lowered active position for engaging a truck bed hook and for operating as a lever to tilt the hand truck under carried loads.
Claim 8
Dependent Claim
121 words
A wheeled hand truck assembly which includes the features of claim 1 above wherein said telescoping frame parts include an inner movable frAme part with space sides, an outer stationary frame part with spaced parts, bearing means carried by the inner frame part to bear against the outer frame part, and bearing means carried by the outer frame part to bear against the inner frame part, a DC electric motor mounted at the bottom of the hand truck, said bearing nut being mounted to a cross member at the top of said inner movable frame part, a bottom cross member between the spaced sides of said inner movable frame part, and an angular toe plate fixed to said bottom cross member.
Claim 9
Dependent Claim
61 words
A wheeled hand truck assembly which includes the features of claim 7 above and which further includes an elongated caster member removably mountable to said toe plate, the long axis of said elongated caster member being normal to the transverse axis of the toe plate, a caster mounted at the opposite end of the elongated caster member to the underside thereof.
Claim 10
Dependent Claim
79 words
A wheeled hand truck assembly which includes the features of claim 8 above and which further includes a strap bar positionable along the length of the movable inner frame part, said strap bar having spaced locking means to frictionally engage spaced sides of the inner frame part when the long axis of the strap bar is parallel to the transverse axis of the toe plate, said locking means being released by pivoting the strap bar about its central portion.
Claim 11
Dependent Claim
155 words
A wheeled hand truck assembly which includes the features of claim 9 above wherein the spaced sides of the frame parts are channel members, the open ends of adjoining channel members of inner and outer frame parts being opposed, said bearing means being rollers fixed to one side of a frame part and rollable in a track of the open channel in an adjacent side of the other frame part, said hand truck assemby further including a U-shaped hooked bar having upright arms and the ends of the upright arms of said U-shaped hook bar being offset and pivotally connected to the insides of channel members of the stationary frame part, said lowering of the upright arms being stopped by an axel member between the frame mounted wheel, the horizontal arm of the hook bar being contacted by the foot of an operator, as well as being engageable to the hook of a truck bed.
References Cited (Backward Citations)
US878546A
Cited
US1986620A
Cited
US2598489A
Cited
US2895567A
Cited
US2904201A
Cited
US3155258A
Cited
US3761107A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |