In
the last post I pointed out that the wheel under a gate could be
eliminated if the gate were built rigid enough to support itself.
'So what', you say? There are probably millions of gates out there
with a wheel under the swing end. In this post we'll look at some of
the reasons that may not be the best way to build a gate.
Rather
than looking at gates with wheels and why they are built that way,
let's look at sound gates and how they are made so they don't need
wheels. No matter what material is used to build a gate, there are
certain principles of physics that apply to all gates and will affect
how they should be designed.
There
is a lot of opinion about bracing on gates, and most of it is based
on anecdotal evidence. You will often hear a gate builder say
something like, “The man who taught me this business has forgotten
more about fence than most other guys know, and he said do it this
way.”
That's great, as long as he forgot all that fence stuff
after
he taught you! All kidding aside, it is a truth in life that the
worst reason to do something in a particular way is that it has
always been done that way. There should be sound reasons behind what
we do, not just tradition backed by emotion. Henry Ford's dad taught
him to hitch a horse to a wagon to move stuff on the farm.
Fortunately, Henry didn't let that stop him from building something
far better.
In
order for a gate to be strong and long lasting, it needs to be rigid. Flex in the system will tend to loosen the connections between
components of the gate, and as this looseness grows, the gate gets
weaker and starts to sag and flex and even lay over. Often it is at
this point that a wheel is added to keep the leading corner from
dragging. This is not a solution. If I break my leg, the doctor can
give me a crutch, and I can get around. If he doesn't set the bone
and cast it so it can heal, (be rigid again), I'll use that crutch
the rest of my life, and the longer I do, the more I wear out my
shoulder, and the other joints in my body because I'm compensating
for the weak leg.
In
the next post we will look at the geometry of a gate and how proper
bracing makes a gate stronger, and improper bracing just makes it
heavier.
