These functions are accomplished by maintaining alignment of the two bearings supporting the tail pulley. This position is generally horizontal and 90 degrees to the belt centerline. Each bearing is mounted on a slide and attached to a hydraulic cylinder. One cylinder is “Reference” and one cylinder is “Follow-up” which is interlocked with the “Reference” cylinder.
The hydraulic system is also electrically interlocked to the starter of the bucket elevator or conveyor. When the starter button is pushed, the hydraulic system is activated. The preset hydraulic system cylinder pressure applies a downward force on the pulley. The downward force is calculated to provide enough tension in the belt to prevent slippage between the belt and the drive pulley. When the preset tension is reached, the bucket elevator or conveyor starts.
If bearing misalignment occurs, it is transmitted from the bearings, through a rope and sheave arrangement to a sensing pin attached to a servo control valve. When the bucket elevator or conveyor is loaded with product, the belt will stretch and the belt pulley moves. Since the system maintains constant hydraulic pressure, the “Reference” cylinder compensates for this movement by taking up the slack. The control valve is actuated and sends a hydraulic flow, proportional to the error, to the “Follow-up” cylinder. The “Follow-up” cylinder then moves in the required direction until the alignment of the bearings is reached.
This same sequence occurs when an abnormal load is applied to one side of the belt, causing the belt to shift. The belt shift produces unequal tension on the bearings and misalignment occurs. The Synchro Take-up/Belt Training System automatically compensates, equalizes the tension on both bearings and thereby centers the belt. Corrections are smooth, fast and proportional to any bearing movement.
The Synchro Take-up/Belt Training System can easily be incorporated into any existing installation and can be supplied as a pull or push system depending on space allocations. In the pull system, the hydraulic cylinders pull the pulley through a chain and sprocket drive attached to the take-up bearings. In the push system, the hydraulic cylinders are attached to the take-up slide above the bearing, pushing the take-up in a downward or horizontal motion.