Dolly with wheel lock

• US 20090026721A1
• Filed: 07/24/2007
• Published: 01/29/2009
• Est. Priority Date: 07/24/2007
• Status: Active Grant

• Current Assignee: Great Star Tools USA, Inc.
• Original Assignee: Shop-Vac Corporation (Hangzhou Great Star Industrial Company Limited)
• Inventors: Martinez, David
• Granted Patent: US 7,758,055 B2
• Time in Patent Office: Days
• US Class Current: 280/79.500
• CPC Class Codes: B62B 5/04 Braking mechanisms; Locking devices against movement
• CPC Class Codes: B62B 5/0433 foot operated
• CPC Class Codes: B62B 5/0485 by braking on the running surface, e.g. the tyre

Abstract

A system for locking the wheels of a dolly for a cleaning device has a brake arm that has one end that is hinged to the base of the dolly. The brake arm pivots between a disengaged position and an engaged position where a stop on an opposite end of the brake arm engages the circumference of one of the wheels on the dolly. A spring biases the brake arm to the disengaged position. The spring can be mounted on a pin that is seated on the base and extends through a slot in the brake arm. An operator-engagable lever is used to move the brake arm from one position to another. The lever can be hinged to the pin, pivoting into and out of a locked position in which the lever presses the brake arm into the engaged position. A cam surface on the lever is shaped so that moving the lever to one side of a critical point causes the lever to be biased toward the locked position, and moving the lever to the other side of the critical point causes the lever to be biased toward the unlocked position. The part of the lever that abuts the brake arm when the lever is in the locked position can be a flat section on the cam surface.

Claims

1. A dolly that is used with a cleaning device, and has:

a base;

a set of parallel wheels;

a brake arm that is hinged to the base and pivots between a) an engaged position in which part of the brake arm acts to retard rotation of one of the parallel wheels and b) a disengaged position in which the brake arm is disengaged from the wheel;

a spring that biases the brake arm to the disengaged position;

an operator-engagable lever that pivots between a) a locked position in which a part of the lever presses the brake arm into the engaged position and b) an unlocked position in which the part of the lever that presses the brake arm into the engaged position is in a different position, enabling the spring to move the brake arm into the disengaged position.

2. A dolly as recited in claim 1, in which:

the dolly also has a pin that is connected to the base and extends through a slot in the brake arm; and

the lever is hinged to an end of the pin.

3. A dolly as recited in claim 1, in which:

the dolly also has a pin that is connected to the base and extends through a slot in the brake arm;

the lever is hinged to an end of the pin; and

the spring is disposed on the pin.

4. A dolly as recited in claim 1, in which:

the dolly also has a pin that extends through a slot in the brake arm;

the spring is disposed around the pin;

the pin has a head on one end;

the base has a hole with a well on an opposite side that holds the head on the pin; and

the lever is hinged to an opposite end of the pin.

5. A dolly as recited in claim 1, in which:

the part of the brake arm that engages the wheel is at one opposed end of the brake arm and the brake arm is hinged to the base at another opposed end of the brake arm;

the brake arm also has a slot that is positioned laterally between the two opposed ends of the brake arm; and

the lever is hinged to a pin that extends through the slot in the brake arm, creating a third class lever that can be used to press the brake arm into the engaged position.

6. A dolly as recited in claim 1, in which:

the part of the brake arm that engages the wheel is at one opposed end of the brake arm and the brake arm is hinged to the base at another opposed end of the brake arm;

the brake arm also has a slot that is positioned laterally between the two opposed ends of the brake arm; and

the spring is disposed on a pin that extends through the slot in the brake arm, creating a third class lever that urges the brake arm to the disengaged position.

7. A dolly as recited in claim 1, in which:

the lever has a first cam surface on one side of a critical point and a second cam surface on an opposite side of the critical point, the first cam surface being configured so that interaction between the lever and the brake arm biases the lever toward the locked position, and the second cam surface being configured so that interaction between the lever and the brake arm biases the lever toward the unlocked position.

8. A dolly as recited in claim 1, in which:

the part of the brake arm that engages the wheel engages the outer circumference of the wheel.

9. A dolly as recited in claim 1, in which:

the part of the brake arm that engages the wheel is at one opposed end of the brake arm and the brake arm is hinged to the base at another opposed end of the brake arm;

the assembly also has a pin that is connected to the base;

the lever is hinged to the pin, creating a third class lever that can be used to press the brake arm toward the engaged position; and

the spring is disposed on the pin, creating a third class lever that urges the brake arm toward the disengaged position.

10. A dolly as recited in claim 1, in which:

the lever has a first cam surface on one side of a critical point and a second cam surface on an opposite side of the critical point, the first cam surface being configured so that interaction between the lever and the brake arm biases the lever toward the locked position, and the second cam surface being configured so that interaction between the lever and the brake arm biases the lever toward the unlocked position; and

the part of the brake arm that engages the wheel engages the outer circumference of the wheel.

11. A dolly as recited in claim 1, in which:

the parallel wheels are on a common axis; and

the axis of the wheels is between 0 and 6 inches behind a pivot on the cleaning device that can be used for dumping a tank.

12. A dolly as recited in claim 1, in which:

the lever has a cam surface with a flat section that presses against the brake arm when the lever is in the locked position.