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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Triple Expansion Steam Engine

Posted by PITHOCRATES - November 6th, 2013

Technology 101

Pressure and Temperature have a Direct Relationship while Pressure and Volume have an Inverse Relationship

For much of human existence we used our own muscles to push things.  Which limited the work we could do.  Early river transport were barges of low capacity that we pushed along with a pole.  We’d stand on the barge and place the pole into the water and into the river bed.  Then push the pole away from us.  To get the boat to move in the other direction.

In more developed areas we may have cleared a pathway alongside the river.  And pulled our boats with animal power.  Of course, none of this helped us cross an ocean.  Only sail did that.  Where we captured the wind in sails.  And the wind pushed our ships across the oceans.  Then we started to understand our environment more.  And noticed relationships between physical properties.  Such as the ideal gas law equation:

Pressure = (n X R X Temperature)/Volume

In a gas pressure is determined my multiplying together ‘n’ and ‘R’ and temperature then dividing this number by volume.  Where ‘n’ is the amount of moles of the gas.  And ‘R’ is the constant 8.3145 m3·Pa/(mol·K).  For our purposes you can ignore ‘n’ and ‘R’.  It’s the relationship between pressure, temperature and volume that we want to focus on.  Which we can see in the ideal gas law equation.  Pressure and temperature have a direct relationship.  That is, if one rises so does the other.  If one falls so does the other.  While pressure and volume have an inverse relationship.  If volume decreases pressure increases.  If volume increases pressure decreases.  These properties prove to be very useful.  Especially if we want to push things.

Once the Piston traveled its Full Stroke on a Locomotive the Spent Steam vented into the Atmosphere 

So what gas can produce a high pressure that we can make relatively easy?  Steam.  Which we can make simply by boiling water.  And if we can harness this steam in a fixed vessel the pressure will rise to become strong enough to push things for us.  Operating a boiler was a risky profession, though.  As a lot of boiler operators died when the steam they were producing rose beyond safe levels.  Causing the boiler to explode like a bomb.

Early locomotives would burn coal or wood to boil water into steam.  The steam pressure was so great that it would push a piston while at the same time moving a connecting rod connected to the locomotive’s wheel.  Once the piston traveled its full stroke the spent steam vented into the atmosphere.  Allowing the pressure of that steam to dissipate safely into the air.  Of course doing this required the locomotive to stop at water towers along the way to keep taking on fresh water to boil into steam. 

Not all steam engines vented their used steam (after it expanded and gave up its energy) into the atmosphere.  Most condensed the low-pressure, low-temperature steam back into water.  Piping it (i.e., the condensate) back to the boiler to boil again into steam.  By recycling the used steam back into water eliminated the need to have water available to feed into the boiler.  Reducing non-revenue weight in steam ships.  And making more room available for fuel to travel greater distances.  Or to carry more revenue-producing cargo.

The Triple Expansion Steam Engine reduced the Expansion and Temperature Drop in each Cylinder

Pressure pushes the pistons in the steam engine.  And by the ideal gas law equation we see that the higher the temperature the higher the pressure.  As well as the corollary.  The lower the temperature the lower the pressure.  And one other thing.  As the volume increases the temperature falls.  So as the pressure in the steam pushes the piston the volume inside the cylinder increases.  Which lowers the temperature of the steam.  And the temperature of the piston and cylinder walls.  So when fresh steam from the boiler flows into this cylinder the cooler temperature of the piston and cylinder walls will cool the temperature of the steam.  Condensing some of it.  Reducing the pressure of the steam.  Which will push the piston with less force.  Reducing the efficiency of the engine.

There was a way to improve the efficiency of the steam engine.  By reducing the temperature drop during expansion (i.e., when it moves the piston).  They did this by raising the temperature of the steam.  And breaking down the expansion phase into multiple parts.  Such as in the triple expansion steam engine.  Where steam from the boiler entered the first cylinder.  Which is the smallest cylinder.  After it pushed the piston the spent steam still had a lot of energy in it looking to expand further.  Which it did in the second cylinder.  As the exhaust port of the first cylinder is piped into the intake port of the second cylinder.

The second cylinder is bigger than the first cylinder.  For the steam entering this cylinder is a lower-pressure and lower-temperature steam than that entering the first cylinder.  And needs a larger area to push against to match the down-stroke force on the first piston.  After it pushes this piston there is still energy left in that steam looking to expand.  Which it did in the third and largest cylinder.  After it pushed the third piston this low-pressure and low-temperature steam flowed into the condenser.  Where cooling removed what energy (i.e., temperature above the boiling point of water) was left in it.  Turning it back into water again.  Which was then pumped back to the boiler.  To be boiled into steam again.

By restricting the amount of expansion in each cylinder the triple expansion steam engine reduced the amount the temperature fell in each cylinder.  Allowing more of the heat go into pushing the piston.  And less of it go into raising the temperature of the piston and cylinder walls.  Greatly increasing the efficiency of the engine.  Making it the dominant maritime engine during the era of steam.

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Trade, Steam Power, Reciprocating Steam Engine, Railroading, Janney Coupler and Westinghouse Air Brake

Posted by PITHOCRATES - January 25th, 2012

Technology 101

Early Cities emerged on Rivers and Coastal Water Regions because that’s where the Trade Was

The key to wealth and a higher standard of living has been and remains trade.  The division of labor has created a complex and rich economy.  So that today we can have many things in our lives.  Things that we don’t understand how they work.  And could never make ourselves.  But because of a job skill we can trade our talent for a paycheck.  And then trade that money for all those wonderful things in our economy.

Getting to market to trade for those things, though, hasn’t always been easy.  Traders helped here.  By first using animals to carry large amounts of goods.  Such as on the Silk Road from China.  And as the Romans moved on their extensive road network.  But you could carry more goods by water.  Rivers and coastal waterways providing routes for heavy transport carriers.  Using oar and sail power.  With advancements in navigation larger ships traveled the oceans.  Packing large holds full of goods.  Making these shippers very wealthy.  Because they could transport much more than any land-based transportation system.  Not to mention the fact that they could ‘bridge’ the oceans to the New World.

This is why early cities emerged on rivers and coastal water regions.  Because that’s where the trade was.  The Italian city-states and their ports dominated Mediterranean trade until the maritime superpowers of Portugal, Spain, The Netherlands, Great Britain and France put them out of business.  Their competition for trade and colonies brought European technology to the New World.  Including a new technology that allowed civilization to move inland.  The steam engine.

Railroading transformed the Industrial Economy

Boiling water creates steam.  When this steam is contained it can do work.  Because water boiling into steam expands.  Producing pressure.  Which can push a piston.  When steam condenses back into water it contracts.  Producing a vacuum.   Which can pull a piston.  As the first useable steam engine did.  The Newcomen engine.  First used in 1712.  Which filled a cylinder with steam.  Then injected cold water in the cylinder to condense the steam back into water.  Creating a vacuum that pulled a piston down.  Miners used this engine to pump water out of their mines.  But it wasn’t very efficient.  Because the cooled cylinder that had just condensed the steam after the power stroke cooled the steam entering the cylinder for the next power stroke.

James Watt improved on this design in 1775.  By condensing the steam back into water in a condenser.  Not in the steam cylinder.  Greatly improving the efficiency of the engine.  And he made other improvements.  Including a design where a piston could move in both directions.  Under pressure.  Leading to a reciprocating engine.  And one that could be attached to a wheel.  Launching the Industrial Revolution.  By being able to put a factory pretty much anywhere.  Retiring the waterwheel and the windmill from the industrial economy.

The Industrial Revolution exploded economic activity.  Making goods at such a rate that the cost per unit plummeted.  Requiring new means of transportation to feed these industries.  And to ship the massive amount of goods they produced to market.  At first the U.S. built some canals to interconnect rivers.  But the steam engine allowed a new type of transportation.  Railroading.  Which transformed the industrial economy.  Where we shipped more and more goods by rail.  On longer and longer trains.  Which made railroading a more and more dangerous occupation.  Especially for those who coupled those trains together.  And for those who stopped them.  Two of the most dangerous jobs in the railroad industry.  And two jobs that fell to the same person.  The brakeman.

The Janney Coupler and the Westinghouse Air Brake made Railroading Safer and more Profitable

The earliest trains had an engine and a car or two.  So there wasn’t much coupling or decoupling.  And speed and weight were such that the engineer could stop the train from the engine.  But that all changed as we coupled more cars together.  In the U.S., we first connected cars together with the link-and-pin coupler.  Where something like an eyebolt slipped into a hollow tube with a hole in it.  As the engineer backed the train up a man stood between the cars being coupled and dropped a pin in the hole in the hollow tube through the eyebolt.  Dangerous work.  As cars smashed into each other a lot of brakemen still had body parts in between.  Losing fingers.  Hands.  Some even lost their life.

Perhaps even more dangerous was stopping a train.  As trains grew longer the locomotive couldn’t stop the train alone.  Brakemen had to apply the brakes evenly on every car in the train.  By moving from car to car.  On the top of a moving train.  Jumping the gap between cars.  With nothing to hold on to but the wheel they turned to apply the brakes.  A lot of men fell to their deaths.  And if one did you couldn’t grieve long.  For someone else had to stop that train.  Before it became a runaway and derailed.  Potentially killing everyone on that train.

As engines became more powerful trains grew even longer.  Resulting in more injuries and deaths.  Two inventions changed that.  The Janney coupler invented in 1873.  And the Westinghouse Air Brake invented in 1872.  Both made mandatory in 1893 by the Railroad Safety Appliance Act.  The Janney coupler is what you see on U.S. trains today.  It’s an automatic coupler that doesn’t require anyone to stand in between two cars they’re coupling together.  You just backed one car into another.  Upon impact, the couplers latch together.  They are released by a lifting a handle accessible from the side of the train.

The Westinghouse Air Brake consisted of an air line running the length of the train.  Metal tubes under cars.  And those thick hoses between cars.  The train line.  A steam-powered air compressor kept this line under pressure.  Which, in turn, maintained pressure in air tanks on each car.  To apply the brakes from the locomotive cab the engineer released pressure from this line.  The lower pressure in the train line opened a valve in the rail car air tanks, allowing air to fill a brake piston cylinder.  The piston moved linkages that engaged the brake shoes on the wheels.  With braking done by lowering air pressure it’s a failsafe system.  For example, if a coupler fails and some cars separate this will break the train line.  The train line will lose all pressure.  And the brakes will automatically engage, powered by the air tanks on each car.

Railroads without Anything to Transport Produce no Revenue

Because of the reciprocating steam engine, the Janney coupler and the Westinghouse Air Brake trains were able to get longer and faster.  Carrying great loads great distances in a shorter time.  This was the era of railroading where fortunes were made.  However, those fortunes came at a staggering cost.  For laying track cost a fortune.  Surveying, land, right-of-ways, grading, road ballast, ties, rail, bridges and tunnels weren’t cheap.  They required immense financing.  But if the line turned out to be profitable with a lot of shippers on that line to keep those rails polished, the investment paid off.  And fortunes were made.  But if the shippers didn’t appear and those rails got rusty because little revenue traveled them, fortunes were lost.  With losses so great they caused banks to fail.

The Panic of 1893 was caused in part by such speculation in railroads.  They borrowed great funds to build railroad lines that could never pay for themselves.  Without the revenue there was no way to repay these loans.  And fortunes were lost.  The fallout reverberated through the U.S. banking system.  Throwing the nation into the worst depression until the Great Depression.  Thanks to great technology.  That some thought was an automatic ticket to great wealth.  Only to learn later that even great technology cannot change the laws of economics.  Specifically, railroads without anything to transport produce no revenue.

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