Hey all: I’ve seen many a type of shifter, and it seems that three of these are most prominant. These three being Mesh shifters, Dog shifters, and Ball-Lock shifters. So here’s my question for you all:
**Which one is the best?
**The goal here is not to end up with a “my shifter turned out better than yours” type discussion, but to hear the technical facts about every type.
My personal opinion is the Ball-Lock shifter. The reason I go with this is due to it’s size and weight difference from the other types. It can take massivley less space, and if done right can be lighter as well.
However, it does have the down side of requiring more advanced machining facilities. Another down side is that it requires more fine parts, and so the risk of breaking something is slightly higher.
I prefer mesh shifting, simplest to manufacture, and for a machine with as short a lifspan as a FIRST robot (you most likley wont be needing thousands of shifts during a competition season, even if you do goto mulitple off-season events), it has plenty of durability
The thing I don’t like about dog shifting is after a while the dog gears can get wobbly because they are only on one bearing. The thing I don’t like about mesh shifting is every one of them I’ve seen is full of metal chips/dust from the shifting. The thing I don’t like about ball shifting is the friction between gear and shaft.
Dog shifting may be a little tougher to make but it requres less space and gears than mesh shifting and is probably more reliable.
You don’t have a planetary shifter listed, a la the Dewalt’s, which is what we’re using this year. Many teams decided to go with them, due to their lightweight, compactness, and cost (<$75.) However, the main drawback with these is that they can only handle one CIM motor.
The required machining is minimal, and mounting is quite simple. I’ve yet to hear about any team that’s had a problem with them, so their robustness can be spoken for. As Dr Joe states, “Even though I design gearboxes for a living, I cannot design a smaller, better, lighter, cheaper, easier to use transmission for FIRST robots.” Based on our experience, I can not argue with that…
Can anyone guess what 222’s choice is? We’ve used the ball lock method three years in a row and every year we keep making improvements. This year’s TigerDrive can be seen here http://www.chiefdelphi.com/forums/showthread.php?t=46470&highlight=tigerdrive Good thread 114ManualLabor, and glad to see popularity growing in the ball lock shifter! To anyone thinking about the ball lock shifter design, don’t be scared of the machining…just ask our students.
We’ve used the ball lock method three years in a row and every year we keep making improvements. This year’s TigerDrive can be seen here