| 摘要 |
<p>A handle (35) mounted generally horizontally on a fork lift truck for controlling forward and reverse speed of movement of the truck and raising and lowering forks is carried by a control device (100). The control device includes a shaft (150) with a centrally positioned spherical section (160) contained in a socket (172, 176) in a support member (170). The shaft is therefore free to rotate about the center (177) of the sphere. A ramp cam (200) is mounted on the support member surrounding the shaft. A slider (180) mounted on the shaft is pressed against the cam by action of a spring (190). This arrangement assures that the shaft and control handle remain centered until acted upon by an operator of the truck. Two linear potentiometers (270, 290) provide electrical output signals representing the X (horizontal) and Y (vertical) positions of the end of the shaft opposite the control handle. The cam is provided with four distinct compound surfaces (201-204). For vertical movement of the handle, the slopes of the two lower surfaces (202, 203) are greater than the slopes of the two upper surfaces (201, 204). The slopes of each surface are also different in the forward and reverse direction. This arrangement provides the illusion that the same force is required to move the handle in any direction. A detent (215) in the center of the cam requires a slightly greater force to move the handle from the center position.</p> |
