we're going to be talking about linear movement two things to consider when talking about linear
movement the first is how you power the linear motion the second is the linear slides that you
are using first type of linear motion we have here is a rack and pinion system and the rack
and pinion system combines both the linear slide and the pieing into one system here's an example
of rack and pinion system moving back and forth if we take a closer look at the system is made of a
few different parts the first is this rack here this is attached to one of the sides of the arm
like this the second is this plastic slide this slots on to the rack itself and holds it next
to the beam the third piece is the pinion here this connects to an axle and drives a movement
of the of the track some advantages of a rack and pinion system is they like I said earlier
it's an all-in-one system that combines both the powering and the slide in the same system another
advantage is that it pulls on both in and out so it is powered in both directions of movement the
last advantage is that it is high torque because it's driven directly by a motor so as a lot of
strength that's pulling down in and out some of the disadvantages of a rack and pinion system
are that the the racks itself are made of plastic so that sometimes prone to breaking another one
the disadvantages is because each state has to be powered by a separate power source the arm
gets very heavy when it's extended as a full extent the second method of power movement is
a string and pulley system now there are two main styles of stringing up the pulleys the
first one is this it is much simpler than the other one but some disadvantages are is that
it's slower because it moves every stage one at a time another advantage of this system is that
you don't need as much torque to pull the arm out the other system is a little bit more complicated
stringing but it moves much faster because it moves all the stages at once some disadvantage
of this system are it requires a lot more torque to pull the arm out this is the first stop string
this isn't what simpler one so it is works is you have one end of the string that is connected to a
winch in this demonstration is going to be my hand pulling this string goes up to the top of
the stage that is fixed to the robot when you pull on this string it pulls this second stage attached
to a pulley closer to that point which extends the arm you continue this going up to the top of
the next stage and then back down to fixed points at the end of the last stage you combine it all
together we can pull on the string it moves all the stages up one at a time like so this is the
second of the key stringing system this one's a little bit more complicated but the advantages are
that it pulls up the arm faster so the way this works this system has two different strings the
first string works just like the other system where you pull on it it is attached to a winch
and a moves the stage up this is connected to the middle stage in this system now because the second
string here in yellow is it's fixed at the bottom of the stage is fixed the robot and it is mounted
with a pulley at the top of the middle stage and back down the bottom of the last stage when you
pull off the middle stage it also causes the last stage to go up there's a wide variety of linear
slides to use for the pulley and winch system these are two of the most common ones here we
have steel drawer slides and here we an 80/20 system we've used both of these systems in the
past we use the drawer slides on the 2015-2016 RESQ season in our robot you can check out our
robot in the robot reveal video on our channel another pros and cons of these systems talk about
the 80/20 some of the pros on is the very strong system use both the beams and linear slides are
very strong pieces another pro of this system is it's very easy to work with all the pieces fit
together well the last is a very smooth motion sliding up and down some of the cons of the
80/20 system are that is very expensive it's also really heavy each of these pieces weighs a lot and
adds a lot of weight to the robot the second of two systems is these steel drawer slides drawer
slides are very cheap and they're very available at many different hardware stores they're also
made of a bunch of different materials such as aluminum these here are steel they are the
cheapest and work the best some of the other pros of this systems is a very smooth motion going in
and out they're also very easy to work with too because you can machine them in different ways
you'd like to use for the arm so the cons of the system are there's a little bit more
flexible than a 80/20 system they are still very heavy because they're made out of steel but some
aluminum ones are available that would make it lighter It's very important to use in competition
and you can use these systems in amazing ways to improve your robot