Scissor lift control apparatus and method

• US 6,330,933 B1
• Filed: 11/29/1999
• Issued: 12/18/2001
• Est. Priority Date: 01/26/1996
• Status: Expired due to Term

• Current Assignee: JLG Industries Incorporated (Oshkosh Corporation)
• Original Assignee: JLG Industries Incorporated (Oshkosh Corporation)
• Inventors: Boeckman, Brian M., Mellott, Lex A.
• Primary Examiner(s): CHIN SHUE, ALVIN C
• Application Number:
  US09/447,948
• Time in Patent Office: 750 Days
• Field of Search: 182/18, 182/19, 182/63.1, 182/2.1, 182/2.11, 182/69.4, 182/69.6
• US Class Current: 182/63.1
• CPC Class Codes: B66F 11/042 actuated by lazy-tongs mechanisms or articulated levers

Abstract

A controller, for a scissor lift control system includes a multiplexing device for lessening the number of conductor lines sent to the controller. The controller includes a microprocessor, and it determines appropriate safe operations of the scissor lift based on various sensed inputs, such as height of the platform and load on the platform. The scissor lift is operated by pushing either a drive select push button, a lift select push button, or a deck select push button. After the switch is selected, the operator has a predetermined amount of time to stroke the joystick in order to effect movement of the scissor lift.

Claims

1. A method for controlling movement of a work platform having a movable platform section with a retractable deck, comprising the steps of:

a) receiving operator inputs on a platform control station housed at the movable platform section, the operator inputs corresponding to a request for one of a drive movement, a lift movement and a deck movement of the work platform;

b) receiving sensed inputs on a plurality of locational conditions of the work platform, including height of the movable platform section;

c) based on the received sensed inputs, either allowing, disallowing, or allowing in a cut back state the request based on the received operator inputs,

wherein in the step a), the operator inputs are made via a plurality of function select switches and a joystick, and wherein the operator has a fixed time period in order to effect movement of the work platform if the request is allowed by stroking the joystick within the fixed time period,

wherein the drive movement can be entered by either a normal drive mode or a high drive mode, said high drive mode allowing for a faster drive speed of the work platform than what is allowable in said normal drive mode, and wherein said work platform can be placed in said high drive mode only when said work platform is currently in said normal drive mode,

the method further comprising the step of;

d) monitoring an amount of current required by a drive motor that performs that drive movement of the work platform when in the normal drive mode and the high drive mode, and when the amount of current exceeds a first value when in said high drive mode, said high drive mode is disabled, and said normal drive mode is entered.

2. The method as recited in claim 1, wherein said high drive mode is maintained until either:

a) said high drive mode is terminated by no operator input for a fixed time period when in said high drive mode, b) a new mode is selected by operator input when in said high drive mode, or c) the current exceeds the first value when in said high drive mode.

3. The method as recited in claim 1, wherein a first of the received sensed inputs corresponds to a load carried by said work platform, and a second of the received sensed inputs corresponds to a signal indicating whether or not said work platform is currently tilted, and

wherein, if said request if for said drive movement, said drive movement is allowed only in the cut-back state so as to only allow said work platform to be driven no greater than a predetermined drive speed.