You’re a mechanical designer at a company that makes machines that manufacture pills. To prevent damage to the pills, you often use helical gears to reduce vibrations. A new hire, Darcy Hogg, emails you for advice. Darcy didn’t learn about helical gears in college and he seems
nervous in his new role at your company. He has worked out specs for helical gears to achieve a 4.4:1 reduction but can’t find the gears in catalogs. In an email, gently correct Darcy’s misunderstandings and offer him advice on selecting gears. You can refer to things like a catalog page but you cannot select the gears for Darcy because you want Darcy to develop independence.
You should catch 4 conceptual errors.
Darcy’s email is as follows:
Hi,
I need help finding gears with the attached specs on McMaster-Carr. I don’t think the website works right. Do you think we should go ahead and get custom gears?
A file is attached showing the specs for a pinion and gear to achieve a reduction of 4.4. I got 4.36. Is that okay?
To make the design as compact as possible, I wanted 11 teeth on the pinion. I picked the specs so the gears would have a ratio of about 4.4, to get the desired reduction. 11 times 4.4 is not an exact integer so I rounded to 48. I picked Q10 and stainless because we want smooth operation and because corrosion could cause problems with FDA approval. I matched the helix and pressure angles on each gear. I put a higher pressure angle on the gear because it carries more force; I also gave the gear a wider face so it could carry double the load. I made sure that both gears were right-handed because that’s the standard. I couldn’t get the diameters on the pinion to line up right so I just copied those numbers over from the Excel calculator for the gear.
You’re a mechanical designer at a company that makes machines that manufacture pills. To prevent damage to the pills, you often use helical gears to reduce vibrations. A new hire, Darcy Hogg, emails you for advice. Darcy didn’t learn about helical gears in college and he seems
nervous in his new role at your company. He has worked out specs for helical gears to achieve a 4.4:1 reduction but can’t find the gears in catalogs. In an email, gently correct Darcy’s misunderstandings and offer him advice on selecting gears. You can refer to things like a catalog page but you cannot select the gears for Darcy because you want Darcy to develop independence.
You should catch 4 conceptual errors.
Darcy’s email is as follows:
Hi,
I need help finding gears with the attached specs on McMaster-Carr. I don’t think the website works right. Do you think we should go ahead and get custom gears?
A file is attached showing the specs for a pinion and gear to achieve a reduction of 4.4. I got 4.36. Is that okay?
To make the design as compact as possible, I wanted 11 teeth on the pinion. I picked the specs so the gears would have a ratio of about 4.4, to get the desired reduction. 11 times 4.4 is not an exact integer so I rounded to 48. I picked Q10 and stainless because we want smooth operation and because corrosion could cause problems with FDA approval. I matched the helix and pressure angles on each gear. I put a higher pressure angle on the gear because it carries more force; I also gave the gear a wider face so it could carry double the load. I made sure that both gears were right-handed because that’s the standard. I couldn’t get the diameters on the pinion to line up right so I just copied those numbers over from the Excel calculator for the gear.