| 摘要 |
In a baseball, softball tennis practice ball throwing machine having a spring actuated pivot arm having a ball impact element at a free end thereof and biasing spring elements at its pivot end. A hand crank is attached to a pivot shaft for rotating the arm against the bias of the spring elements. A ball support station is provided to support a ball in the path of the ball impact element to be impacted and projected a distance by the arm as it rapidly rotate about the pivot shaft when under the influence of the biasing spring elements.
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