Tow truck with underlift control

• US 20080279667A1
• Filed: 05/11/2007
• Published: 11/13/2008
• Est. Priority Date: 05/11/2007
• Status: Active Grant

• Current Assignee: Jerr-Dan Corporation (Oshkosh Corporation)
• Original Assignee: Oshkosh Corporation
• Inventors: Kresge, Bradley S., Addleman, Jeffrey L.
• Granted Patent: US 7,909,561 B2
• Time in Patent Office: Days
• US Class Current: 414/563
• CPC Class Codes: B60P 3/125 by supporting only part of the vehicle, e.g. front- or rear-axle
• CPC Class Codes: B66F 9/061 characterised by having a lifting jib

Abstract

A vehicle includes a chassis and an underlift supported by the chassis. The underlift includes a boom including a vehicle engaging device coupled to the boom and a movement actuator for moving the boom. The underlift further includes a control system configured to restrict actuation of the movement actuator when the boom moves to a predetermined position; and an operator control coupled to the control system that allows the operator to control the movement actuator after actuation of the movement actuator has been restricted.

Claims

1. A vehicle comprising:

a chassis;

an underlift supported by the chassis, the underlift comprising;

a boom including a vehicle engaging device coupled to the boom; and

a movement actuator for moving the boom;

a control system configured to restrict actuation of the movement actuator when the boom moves to a predetermined position;

an operator control coupled to the control system that allows the operator to control the movement actuator after actuation of the movement actuator has been restricted.

2. The vehicle of claim 1, wherein the vehicle engaging device and movement actuator are generally located at opposite ends of the boom.

3. The vehicle of claim 2, the underlift further comprising a position sensor to detect a predetermined loading position of the boom.

4. The vehicle of claim 1, wherein the movement actuator is a hydraulic cylinder.

5. The vehicle of claim 1, wherein the movement actuator rotates the boom about a pivot.

6. The vehicle of claim 1, wherein the movement actuator rotates the boom about a pivot in at least a downward direction.

7. The vehicle of claim 1, further comprising a position sensor configured to detect a predetermined loading height of the boom.

8. The vehicle of claim 7, wherein the control system is further configured to restrict actuation of the movement actuator when the predetermined loading height is detected by the position sensor;

and the control system allows the operator to actuate the movement actuator after the predetermined loading height is detected so that the boom may continue movement in a downward direction.

9. The vehicle of claim 1, wherein the control system comprises a time delay relay configured to restrict an actuating signal sent to the movement actuator when the predetermined position is reached.

10. The vehicle of claim 1, further comprising a position sensor that is a switch that breaks a movement actuating circuit between the operator control and the movement actuator.

11. The vehicle of claim 10, wherein the vehicle further comprises an operator bypass switch that recompletes the actuating circuit.

12. The vehicle of claim 10, wherein the control system is configured to wait until the operator has released an operator control that was causing a downward motion before allowing the operator to then signal the movement actuator to actuate further downward.

13. The vehicle of claim 10, wherein the position sensor is a switch that resets when the boom has moved back to or above the predetermined position from a position below the predetermined location.

14. A method for controlling the movement of a vehicle underlift boom, comprising:

causing underlift boom movement in response to an actuating signal from an operator control;

generating a position signal;

inhibiting underlift boom movement based upon the position signal; and

resuming underlift boom movement in response to input from the operator control.

15. The method of claim 14, further comprising waiting a period of time after inhibiting underlift boom movement and before allowing the operator control to resume underlift boom movement.

16. The method of claim 14, wherein receiving input from the operator control to resume movement comprises receiving a bypass signal.

17. The method of claim 14, further comprising receiving input from the operator control to resume movement.

18. The method of claim 17, wherein receiving input from the operator control to resume movement comprises receiving an indication that the operator has at least momentarily released any control that was causing the actuating signal.

19. The method of claim 14, wherein the boom rotates downward in response to the signal.

20. The method of claim 15, wherein the predetermined boom position is a default loading position.

21. The method of claim 20, wherein the boom is positioned slightly above and parallel to a ground plane along the length of the boom when the boom is in the default loading position and vehicle is on flat ground.

22. A vehicle underlift supportable by a vehicle chassis, the underlift comprising:

a vehicle engaging device;

a movement actuator for moving the vehicle engaging device;

a control system configured to restrict actuation of the movement actuator when the vehicle engaging device moves to a predetermined position; and

an operator control coupled to the control system that allows the operator to selectively actuate the movement actuator after actuation of the movement actuator has been restricted.

23. An underlift control circuit for controlling at least one underlift movement actuator, the control circuit comprising:

an operator interface configured to apply a control signal to the control circuit;

an underlift position sensor configured to apply a position signal to the control circuit;

the control circuit configured to operate at least one underlift movement actuator in response to the control signal until the position signal changes in a predetermined way, operation of the underlift movement actuator being inhibited until there is a change in the control signal.

24. The underlift control circuit of claim 23, wherein the underlift control circuit further comprises:

a relay configured to complete or break the communicative circuit between the operator interface and the movement actuator; and

a silicon controlled rectifier configured to latch the relay in a circuit breaking state when the gate of the silicon controlled rectifier is pulsed by the position signal, the position signal pulsing when a default loading position has been reached.

25. The underlift control circuit of claim 24, wherein the silicon controlled rectifier and relay are configured to remain latched in the circuit breaking state until an operator discontinues the underlift actuating signal coming from the operator interface.