Snow Blowers

Posted by PITHOCRATES - January 29th, 2014

Technology 101

If you try to Push or Lift too much Snow you can Wrench your Back, Give yourself a Hernia or Have a Heart Attack

It’s funny, isn’t it?  How much we love to see a white Christmas.  Nothing brings a bigger smile on our face than to see a white blanket out of our windows during the Christmas holiday.  It’s so pretty.  Pristine.  And pure.  Just like the true meaning of Christmas.  But once Christmas comes and goes and that white stuff is still out there our feelings change.  It’s no longer pretty, pristine and pure.  It’s just more of that white [deleted expletive] that we have to shovel.

If you have a detached garage you’re probably no fan of the snow.  Because with every snow fall you have hours of work ahead of you.  To shovel the front sidewalk so the city doesn’t fine you.  The sidewalk up to your mailbox for the mail carrier.  So he or she doesn’t slip and die on your property.  And then that long driveway.  From the approach in the street (so you don’t get stuck in the loose snow there) all of the way into your backyard and to that detached garage.  Over an hour by hand if the snow isn’t too deep.  Or you can let the snow stay there.  Melt a little during the day.  Freeze a little at night.  So you can slip on it and fall.  Breaking your hip.

Of course that snow shoveling would be quicker if you had a shovel as wide as the driveway.  But if we did we would never be able to lift the snow in it.  Because snow is heavy.  And if you try to push or lift too much of it you can wrench your back, give yourself a hernia or have a heart attack.  Which is why we use snow shovels much smaller than the width of the driveway.  It’ll take a lot more time to shovel the snow off it.  But our odds are greatly reduced for getting a wrenched back, hernia or heart attack.

The Two-Stage Snow Blower is not very Maneuverable but it can move through Deep Snow and throw it a Long Way

Snow is heavy.  And the wetter it is the heavier it is.  And the greater risks there are shoveling it.  Which is why God gave us the snow blower.  Or, rather, gave us Robert Carr Harris who gave us the snow blower in 1870.  Which has evolved into two basic machines today.  The single-stage snow blower.  And the 2-stage snow blower.  One of which is ideal for around the house.  The single-stage snow blower.  While the other is ideal for bigger jobs.  Where we have to move a lot more snow than what just falls around our house.  Though there are homeowners who use a 2-stage snow blower.  Even though a single-stage would be more appropriate.

A 2-stage snow blower can be a beast.  Taking up the footprint of a riding lawnmower.  It’s big.  And heavy.  Too heavy for most people to push through the snow.  Which is why these are typically self-propelled.  Requiring a bigger engine.  And a complicated gear box.  To divide the power between the ‘throwing’ function and the ‘propelling’ function.  The throwing function has two stages.  An auger in the front that turns slowly (requiring more gearing) to eat into the snow and pull it towards the center.  At the center is an impeller that turns much faster than the auger .  As the snow is slowly pushed into the fast-spinning impeller it throws the snow into and out of a directional discharge chute at a fast speed.  Throwing it a great distance.

It takes a fairly large engine to spin the auger, the impeller and the drive wheels.  And it takes a pretty complicated (and large and heavy) gear box to provide various rotational speeds for the various components.  As well as a large frame to hold these components, the drive wheels, controls, safety interlocks, oil and fuel.  Making the two-stage snow blower not that nimble or maneuverable.  Which isn’t a problem if you’re walking back and forth over a long driveway.  But it can be a big problem on a sidewalk with a turn or a curve in it.  For turning these beasts can take some muscle.  Muscle that we apply with our feet on a slippery surface.  Even after we’ve already cleared the deep snow off with the snow blower.  For the auger does not come into contract with the pavement.  Meaning it doesn’t clear away the snow down to the pavement.  But it can move through deep snow and throw it a long way.  Making it ideal for big jobs.

The Advantage of a 2-Cycle Engine is a High Power-to-Weight Ratio making it Ideal for a Single-Stage Snow Thrower

The single-stage snow blower is much lighter.  For it has only a fast-spinning auger.  It eats into the snow, pulls it towards the center and throws it out the discharge chute.   Without an impeller.  Throwing it a pretty fair distance.  And the auger actually comes into contract with the ground.  Which helps pull it forward.  And cleans down to the pavement.  With the only one spinning component there are no heavy gear boxes providing multiple speeds to different components.  Making the single-stage snow blower much lighter.  And easier to maneuver.  And it typically has a 2-cycle (or 2-stroke) engine.  Making it lighter still.

The typical engine on a 2-stage snow blower is a 4-cycle (or 4-stroke) engine.  Where the piston moves up or down 4 times to create power.  It moves down and draws in an air-fuel mixture through an intake valve.  It moves up and compresses the air-fuel mixture.  A spark plug ignites this and the hot expanding gases push the piston down on its power stroke.  And then the piston comes up and pushes the exhaust gases out of the cylinder through an exhaust valve.  Then repeats.  A 2-cycle engine has fewer moving parts.  And half the strokes.  As the air-fuel-oil mixture ignites the hot gases push the piston down.  As the top of the piston moves past exhaust ports the exhaust gases can exit the cylinder.  At the same time an air-fuel-oil mixture enters the cylinder through intake ports on the other side of the cylinder.  The piston moves up and compresses this, ignites and pushes the piston down.  Then repeats.

The advantage of a 2-cycle engine is a high power-to-weight ratio.  Allowing a smaller 2-cycle engine to do the work of a comparable 4-cycle engine.  Making them ideal for a single-stage snow blower.  The disadvantage of a 2-cycle engine is that the crank case is used to draw in the air-fuel mixture on the up-stroke of the piston.  And then the piston pushed the air-fuel mixture out of the crankcase and into the cylinder on the down-stroke of the piston.  Because the crankcase is used as part of the pathway for the air-fuel mixture it cannot hold oil.  Which is why we mix oil in the fuel.  Giving us an air-fuel-oil mixture that combusts in the cylinder.  The moving components get lubricated as this mixture travels through the engine.  Which is perhaps the biggest drawback of the single-stage snow blower.  Having to mix oil with gas.  It’s not difficult.  You just have to make sure you add the right amount of oil.  And not to use this gas-oil mixture in your 4-cycle lawnmower.  And even though we were never big fans of cutting the grass even that begins to look pretty sweet as the snow blows back in our face as we walk behind our snow blowers.  Thinking of but one thing.  Spring.  And thanks to these wonderful machines we may actually make it to spring healthy.  Without having suffered a wrenched back, hernia or a heart attack.

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Steam Locomotive

Posted by PITHOCRATES - November 13th, 2013

Technology 101

The Steam Locomotive was one of the Few Technologies that wasn’t replaced by a Superior Technology 

Man first used stone tools about two and a half million years ago.  We first controlled fire for our use about a million years ago.  We first domesticated animals and began farming a little over 10,000 years ago.  The Egyptians were moving goods by boats some 5,000 years ago.  The Greeks and Romans first used the water wheel for power about 2,500 years ago. The Industrial Revolution began about 250 years ago.  James Watt improved the steam engine about 230 years ago.  England introduced the first steam locomotive into rail service about 210 years ago. 

In the first half of the 1800s the United States started building its railroads.  Helping the North to win the Civil War.  And completing the transcontinental railroad in 1869.  By 1890 there were about 130,000 miles of track crisscrossing the United States.  With the stream locomotives growing faster.  And more powerful.  These massive marvels of engineering helped the United States to become the number one economic power in the world.  As her vast resources and manufacturing centers were all connected by rail.  These powerful steam locomotives raced people across the continent.  And pulled ever longer—and heavier—freight trains.

We built bigger and bigger steam locomotives.  That had the power to pull freight across mountains.  To race across the Great Plains.  And into our cities.  With the chugging sound and the mournful steam whistle filling many a childhood memories.  But by the end of World War II the era of steam was over.  After little more than a century.  Barely a blip in the historical record.  Yet it advanced mankind in that century like few other technological advances.   Transforming the Industrial Revolution into the Second Industrial Revolution.  Or the Technological Revolution.  That gave us the steel that built America.  Electric Power.  Mass production.  And the production line.  None of which would have happened without the steam locomotive.  It was one of the few technologies that wasn’t replaced by a superior technology.  For the steam locomotive was more powerful than the diesel-electric that replaced it.  But the diesel-electric was far more cost-efficient than the steam locomotive. Even if you had to lash up 5 diesels to do the job of one steam locomotive.

The Hot Gases from the Firebox pass through the Boiler Tubes to Boil Water into Steam

The steam engine is an external combustion engine.  Unlike the internal combustion engine the burning of fuel did not move a piston.  Instead burning fuel produced steam.  And the expansion energy in steam moved the piston.  The steam locomotive is a large but compact boiler on wheels.  At one end is a firebox that typically burned wood, coal or oil.  At the other end is the smokebox.  Where the hot gases from the firebox ultimately vent out into the atmosphere through the smokestack.  In between the firebox and the smokebox are a bundle of long pipes.  Boiler tubes.  The longer the locomotive the longer the boiler tubes. 

To start a fire the fireman lights something to burn with a torch and places it on the grating in the firebox.  As this burns he may place some pieces of wood on it to build the fire bigger.  Once the fire is strong he will start shoveling in coal.  Slowly but surely the fire grows hotter.  The hot gases pass through the boiler tubes and into the smokebox.  And up the smoke stack.  Water surrounds the boiler tubes.  The hot gases in the boiler tubes heat the water around the tubes.  Boiling it into steam.  Slowly but surely the amount of water boiled into steam grows.  Increasing the steam pressure in the boiler.  At the top of the boiler over the boiler tubes is a steam dome.  A high point in the boiler where steam under pressure collects looking for a way out of the boiler.  Turned up into the steam dome is a pipe that runs down and splits into two.  Running to the valve chest above each steam cylinder.  Where the steam pushes a piston back and forth.  Which connects to the drive wheels via a connecting rod.

When the engineer moves the throttle level it operates a variable valve in the steam dome.  The more he opens this valve the more steam flows out of the boiler and into the valve chests.  And the greater the speed.  The valve in the valve chest moved back and forth.  When it moved to one side it opened a port into the piston cylinder behind the piston to push it one way.  Then the valve moved the other way.  Opening a port on the other side of the piston cylinder to allow steam to flow in front of the piston.  To push it back the other way.  As the steam expanded in the cylinder to push the piston the spent steam exhausted into the smoke stack and up into the atmosphere.  Creating a draft that helped pull the hot gases from the firebox through the boiler tubes, into the smokebox and out the smoke stack.  Creating the chugging sound from our childhood memories.

The Challenger and the Big Boy were the Superstars of Steam Locomotives

To keep the locomotive moving required two things.  A continuous supply of fuel and water.  Stored in the tender trailing the locomotive.  The fireman shoveled coal from the tender into the firebox.  What space the coal wasn’t occupying in the tender was filled with water.  The only limit on speed and power was the size of the boiler.  The bigger the firebox the hotter the fire.  And the hungrier it was for fuel.  The bigger locomotives required a mechanized coal feeder into the firebox as a person couldn’t shovel the coal fast enough.  Also, the bigger the engine the greater the weight.  The greater the weight the greater the wear and tear on the rail.  Like trucks on the highway railroads had a limit of weight per axel.  So as the engines got bigger the more wheels there were ahead of the drive wheels and trailing the drive wheels.  For example, the Hudson 4-6-4 had two axels (with four wheels) ahead of the drive wheels.  Three axles (with 6 wheels) connected to the pistons that powered the train.  And two axels (with four wheels) trailing the drive wheels to help support the weight of the firebox.

To achieve ever higher speeds and power over grades required ever larger boilers.  For higher speeds used a lot of steam.  Requiring a huge firebox to keep boiling water into steam to maintain those higher speeds.  But greater lengths and heavier boilers required more wheels.  And more wheels did not turn well in curves.  Leading to more wear and tear on the rails.  Enter the 4-6-6-4 Challenger.  The pinnacle of steam locomotive design.  To accommodate this behemoth on curves the designers reintroduced the articulating locomotive.  They split up the 12 drive wheels of the then most powerful locomotive in service into two sets of 6.  Each with their own set of pistons.  While the long boiler was a solid piece the frame underneath wasn’t.  It had a pivot point.  The first set of drive wheels and the four wheels in front of them were in front of this pivot.  And the second set of drive wheels and the trailing 4 wheels that carried the weight of the massive boiler on the Challenger were behind this pivot.  So instead of having one 4-6-6-4 struggling through curves there was one 4-6 trailing one 6-4.  Allowing it to negotiate curves easier and at greater speeds.

The Challenger was fast.  And powerful.  It could handle just about any track in America.  Except that over the Wasatch Range between Green River, Wyoming and Ogden, Utah.  Here even the Challenger couldn’t negotiate those grades on its own.  These trains required double-heading.  Two Challengers with two crews (unlike lashing up diesels today where one crew operates multiple units from one cab).  And helper locomotives.  This took a lot of time.  And cost a lot of money.  So to negotiate these steep grades Union Pacific built the 4-8-8-4 articulated Big Boy.  Basically the Challenger on steroids.  The Big Boy could pull anything anywhere.  The Challenger and the Big Boy were the superstars of steam locomotives.  But these massive boilers on wheels required an enormous amount of maintenance.  Which is why they lasted but 20 years in service.  Replaced by tiny little diesel-electric locomotives.  That revolutionized railroading.  Because they were so less costly to maintain and operate.  Even if you had to use 7 of them to do what one Big Boy could do.

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