Fig 13 shows a hand-operated food mincer used in a kitchen for processing meat and vegetables. The mincer uses a mechanism to convert the rotary motion of a...
Question 1 Report
Fig 13 shows a hand-operated food mincer used in a kitchen for processing meat and vegetables. The mincer uses a mechanism to convert the rotary motion of a hand crank into the forward linear motion of food through a cylindrical barrel. Inside the mechanism housing, a pair of spur gears reduces the crank speed and increases the torque applied to an auger screw that pushes the food toward a cutting plate at the outlet. The spur gears have straight-cut teeth that mesh within the cast iron body of the mincer. A lever clamp at the base of the mincer secures it firmly to the kitchen worktop during use, preventing the mechanism from moving under the reaction forces generated during operation. The fig shows the arrangement of the crank handle, spur gears, auger and lever clamp on the assembled mincer.
(a) Give one advantage of using spur gears in this mechanism to increase the torque at the auger screw. [1]
(b) Name the type of motion produced by the food as the auger pushes it through the barrel. [1]
(c) Give one reason why the lever clamp is important for the safe operation of this mechanism. [1]
Answer Details
(a) The spur gears provide a mechanical advantage that increases the torque (turning force) at the auger screw. [1] The gear reduction means the driver gear on the crank turns faster than the driven gear on the auger shaft, so the output torque is multiplied relative to the input. This allows the operator to process tough or fibrous food through the barrel with less physical effort at the hand crank than would be required with a direct drive connection.
(b) The food produces linear motion as the auger pushes it through the barrel. [1] The food travels in a straight line along the length of the cylindrical barrel toward the cutting plate at the outlet. The helical auger screw converts its own rotary motion into a linear pushing force on the food, feeding it forward continuously.
(c) The lever clamp holds the mincer firmly to the worktop, preventing it from sliding, tipping, or rotating during operation. [1] Without the clamp, the reaction forces from the auger mechanism (particularly the torque reaction when processing tough food) would cause the mincer to move, which could pull the operator's hand into the feeding tube or cause the mincer to fall from the worktop.
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