| 摘要 |
A computer controlled braking system utilizes gross vehicle weight of a materials handling vehicle and maximum allowable vehicle speeds to calculate braking force in response to a service brake request. For vehicles equipped with a caster brake, the calculated braking force is proportionally distributed between a drive brake and the caster brake. The drive brake includes a mechanical brake and motor braking which is performed by a traction motor. The drive brake force is divided between the mechanical brake and the motor braking so that the motor provides as much braking as possible to reduce wear on the mechanical brake and also to conserve battery power. For vehicles equipped with a caster brake, the caster brake portion of the calculated braking force is determined as a programmable percentage of the total braking force and can differ based on travel direction. The caster brake portion is clipped and reverts to the drive brake if it is below a minimum; and, if the calculated caster brake force is greater than a maximum, the caster brake force in excess of the maximum is clipped and reverts to the drive brake. A maximum caster brake current can be set to accommodate different brake hardware. A user of the vehicle can select adjustments to the calculated drive brake force and, if provided, can also select independent adjustments to the calculated caster brake force. If the vehicle has not substantially stopped within a given period of time after having its speed reduced to a low speed, the mechanical drive brake is fully applied.
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