A driving mechanism of a planer consists of an electric motor situated over the housing. The motor shaft is coupled with a counter shaft. The counter shaft, at its extreme end, carries two driving pulleys: one for open belt and other for cross belt. The main driving shaft is provided below the bed. Its one end passes through the housing and carries a pinion, which meshes with the rack provided under the table of the machine. The other end of the shaft carries two pairs of pulleys; each pair consists of a fast pulley and a loose pulley. One of these pairs is connected to one of the driving pulleys by means of an open belt and the other to the second driving pulley by means of crossed belt. A speed reduction gear box is mounted on the main driving shaft and same is incorporated between the pinion and the pairs of driven pulleys. The driving mechanism is shown in Figure 19.28.
One set of the above pulleys is used for forward motion and other set for backward motion of the table. The cross belt is used for forward motion and open belt is used for backward motion. The driving pulley on counter shaft for cross belt is smaller than the pair of fast and loose pulleys for the same. While the driving pulley on the driving shaft for open belt is bigger than the pair of fast and loose pulley on the same. This arrangement is provided for slow forward stroke and fast backward stroke.
The pulleys are so arranged that when the cross belt is on fast pulley, i.e., in forward stroke, the open belt will be on the loose pulley and its reverse will take place during return stroke. The relative shifting of belt may take place automatically at the end of each stroke, without stopping the machine; a belt shifter and its operating lever are provided on the machine. Trip dogs are mounted at both ends of the table. At the end of each stroke, these dogs strike against the operating lever alternately and the belt shifted accordingly. Thus, table movement is reversed automatically.
Figure 19.28 Driving Mechanism of Planer
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