| 摘要 |
A system for controlling the speed of an engine in a vocational application is implemented within a mobile cement mixer. The system permits operation of the engine at a high rpm PTO speed to drive the mixing drum at a recommended speed for optimal full mixing of aggregate within the drum. The system maintains the engine at this high rpm only for a predetermined time period necessary for full mixing. After expiration of the time period, the system directs the engine governor to drop the engine speed to low idle, thereby preventing overworking of the cement, reducing the abrasive effect of the aggregate on the interior of the mixing drum, and improving engine fuel economy. In one embodiment, the system permits operator entry of drum rotation speed and total drum revolutions, which are then used to calculate the time period value. In another embodiment, the input is number of drum rotations and the system uses a signal from a drum rotation counter to control the high rpm-low idle speed change of the engine.
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