# Why do pitching machines use wheels and not solenoids, actuators, servos or peumatic cylenders?

I guess that generating movement is harder then keeping a wheel rolling, but in terms of power consumption is it possible to compare the power consumption of a motor for driving wheels to that of a circuit that charges a capacitor and powers a solenoid? Running on high voltage solenoids can be very fast and powerful, and also pneumatic cylinders can be very fast.

Let's say we talk about a 5g ball that is shot at a speed of 10m/s.

Will the preferred motor be different for different weights and speeds? E.g. will an actuator be the choice for heavy and slow situation? Why?

• For reference baseballs weigh 140 g, cricket balls 160 g, and tennis balls weigh 60 g. I imagine those are the most frequently pitched balls. – wwarriner Oct 16 '19 at 23:37
• Something to consider. How complex is a wheel based pitching machine & how complex would such a machine be that used solenoids etc. Simplicity of operation &/or manufacture just might be the deciding factors. – Fred Oct 17 '19 at 2:01
• @wwarriner You forgot ping pong balls that weight 2.7g. – OMGsh Oct 17 '19 at 6:18
• True! If you need ping pong balls in particular you might work that into your question. Based on the assumption in your question (5 g weight) that might be worth specifying. If not, then its worth thinking about the effort it takes a human to accelerate say a baseball to 80 mph, and what size/cost solenoids would be required. – wwarriner Oct 17 '19 at 12:45

Two reasons.

• The wheels take advantage of release energy of squeezing and compressing the ball. So they don't have to accelerate the ball to its final velocity; it wants to jump out by itself.

• The turning wheel acts as a flywheel, preserving the angular momentum, reducing power needed to a smaller average.

• Plus, with two drums a different speeds, you can get curve balls. – Eric S Oct 19 '19 at 23:00
• @Eric Shaun, right. – kamran Oct 20 '19 at 4:17