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Re: Simple Machines B/Compound Machines C

Posted: March 23rd, 2015, 5:43 pm
by UTF-8 U+6211 U+662F
mjcox2000 wrote:
UTF-8 U+6211 U+662F wrote:
UTF-8 U+6211 U+662F wrote:Reviving this thread:
Question for Simple Machines:
Who identified the pulley?
Oops, that's not the right question. :oops:
Instead, define a spur gear.
A gear, whose cross-section (perpendicular to the axis of rotation) is the same at all heights along the gear, having an integral number of teeth projecting out radially, each tooth at a constant angle from those next to it.
Wow, that's a much more high-quality answer than I expected :D Okay, your turn!

Re: Simple Machines B/Compound Machines C

Posted: March 25th, 2015, 4:20 pm
by mjcox2000
Explain how spur gears, helical gears, herringbone gears, and worm gears differ, and the merits and faults of each of those gear types.

Re: Simple Machines B/Compound Machines C

Posted: March 25th, 2015, 5:40 pm
by UTF-8 U+6211 U+662F
EDIT: nvm I have no idea.

Re: Simple Machines B/Compound Machines C

Posted: March 25th, 2015, 5:48 pm
by Unome
Spur gears are standard gears useful for changing torque, speed or rotational direction of motion; however, they stick easily. Worm gears have low efficiency, but can be used in some specialized situations where a lot of friction is required (ex. screws). I can't remember what helical and herringbone gears are.

Re: Simple Machines B/Compound Machines C

Posted: March 26th, 2015, 3:43 pm
by UTF-8 U+6211 U+662F
Unome wrote:
Spur gears are standard gears useful for changing torque, speed or rotational direction of motion; however, they stick easily. Worm gears have low efficiency, but can be used in some specialized situations where a lot of friction is required (ex. screws). I can't remember what helical and herringbone gears are.
curved gear (angled teeth)
type of double helical gear
Still have no idea though! :lol:

Re: Simple Machines B/Compound Machines C

Posted: March 26th, 2015, 5:50 pm
by mjcox2000
UTF-8 U+6211 U+662F wrote:
Unome wrote:
Spur gears are standard gears useful for changing torque, speed or rotational direction of motion; however, they stick easily. Worm gears have low efficiency, but can be used in some specialized situations where a lot of friction is required (ex. screws). I can't remember what helical and herringbone gears are.
curved gear (angled teeth)
type of double helical gear
Still have no idea though! :lol:
You've both touched on it, but didn't quite give all the details I was expecting.
Spur gear: Simplest gear type. Teeth protrude out radially from a gearwheel; cross-section is the same at all heights. Spur gears can mesh with one another for a mechanical advantage.
Helical gear: Similar to a spur gear; however, the teeth are not vertical, but wrapped around the outside of the gearwheel at a certain angle from vertical (i.e. each tooth can be thought of as part of a helix). Helical gears mesh with other helical gears with teeth offset from vertical at the same angle. They are used because a greater 
Herringbone gear: Two helical gears, placed back-to-back. They have the benefits of a helical gear (increased surface area), but without the sideways thrust. A herringbone gear meshes with another herringbone gear.
Worm gear: A helical gear with teeth wrapping more than a full rotation around the gearwheel (i.e. a screw). A worm gear often has only one tooth. Worm gears drive [b]spur or helical gears[/b], not other worm gears. They always have an IMA greater than 1.
Your turn (either one of you - whoever posts a question first can go).

Re: Simple Machines B/Compound Machines C

Posted: March 26th, 2015, 5:52 pm
by Unome
mjcox2000 wrote:
UTF-8 U+6211 U+662F wrote:
Unome wrote:
Spur gears are standard gears useful for changing torque, speed or rotational direction of motion; however, they stick easily. Worm gears have low efficiency, but can be used in some specialized situations where a lot of friction is required (ex. screws). I can't remember what helical and herringbone gears are.
curved gear (angled teeth)
type of double helical gear
Still have no idea though! :lol:
You've both touched on it, but didn't quite give all the details I was expecting.
Spur gear: Simplest gear type. Teeth protrude out radially from a gearwheel; cross-section is the same at all heights. Spur gears can mesh with one another for a mechanical advantage.
Helical gear: Similar to a spur gear; however, the teeth are not vertical, but wrapped around the outside of the gearwheel at a certain angle from vertical (i.e. each tooth can be thought of as part of a helix). Helical gears mesh with other helical gears with teeth offset from vertical at the same angle. They are used because a greater 
Herringbone gear: Two helical gears, placed back-to-back. They have the benefits of a helical gear (increased surface area), but without the sideways thrust. A herringbone gear meshes with another herringbone gear.
Worm gear: A helical gear with teeth wrapping more than a full rotation around the gearwheel (i.e. a screw). A worm gear often has only one tooth. Worm gears drive [b]spur or helical gears[/b], not other worm gears. They always have an IMA greater than 1.
Yeah... something I'll have to memorize out of the binder for Nationals (although last year's test wasn't that difficult, so I'm not really sure what to expect)

Re: Simple Machines B/Compound Machines C

Posted: March 26th, 2015, 6:17 pm
by UTF-8 U+6211 U+662F
I still have no idea. So, I'm presuming mjcox is asking another question?

Re: Simple Machines B/Compound Machines C

Posted: March 26th, 2015, 6:18 pm
by Unome
UTF-8 U+6211 U+662F wrote:I still have no idea. So, I'm presuming mjcox is asking another question?
Hopefully. His questions are good.

Re: Simple Machines B/Compound Machines C

Posted: March 26th, 2015, 6:24 pm
by UTF-8 U+6211 U+662F
Unome wrote:
UTF-8 U+6211 U+662F wrote:I still have no idea. So, I'm presuming mjcox is asking another question?
Hopefully. His questions are hard.
Of course, I barely studied! :lol: