Thursday, February 28, 2008

Zen and the Art of Icemaking - Part 2

OK, assuming you've all done your homework and read about "how the Zamboni works" I'll take you along for a 'virtual' ride-a-long and describe the actual operation.

For this example, we'll use the Zamboni Model 520 - the main machine at USBA. This model uses a Ford 2.3 litre industrial engine for its powerplant. Like all modern Zamboni machines, it uses a hydrastatic transmission. This is a hydraulic propulsion system, similar to a military tank. There are no gears, the transmission lever just allows it to go faster the further it is pushed.

Top speed: about 9 mph.

There are two control levers at the driver's right hand. One is that transmission lever. The further you push it, the faster the machine can go. The second lever is the throttle setting. This sets the engine RPM's (the "gas pedal" is not gas on this machine). Typically for icemaking operations the tachometer is set at 2500-2700 RPMs; this is necessary to power all the hydraulics for the engine, moving the augers, the conditioner, etc. and keep that snow moving up into the tank.

The "gas pedal" is actual more like a clutch on the hydrastatic transmission. Effectively, it does the same thing - the further you press down, the faster it goes. But technically it is controlling the hydraulic flow and not the engine. It is not perfectly automatic. The driver has to be careful not to "floor it" too fast, or let off too fast. It sends that throttle control into a frenzy trying to adjust.

So, a driver must smoothly make speed changes with the foot pedal to keep everything moving smoothly. If he crams it to the floor, it will just bog down. If he is going fast and lets off too fast, the throttle drops and the augers lose efficiency to move snow for a few moments - but that can be enough to get it too far behind to work right.

Smooth. Ummmmmmmmm. Smooth.

So, we drive out onto the ice, usually with the transmission lever at max and the throttle at about 1500 RPM. Once on the ice, the throttle is moved to about 2600 and then the conditioner is lowered all the way onto the ice. This is done with one of the four small levers to the right of the back of the driver's seet.

Then the augers (conveyors) need to be started. This is also done with two levers in that set of four. I usually turn the vertical on first so it is ready to receive it's snow. During this time the snow is collecting between the blade and the horizontal conveyor. Then I start that conveyor. It only takes a couple of seconds. Since I have big hands, sometimes I start them both at the same time, using my thumb and first finger.

Next the shaving blade needs to be checked and adjusted if necessary. Before the water is turned on, the driver can look over his shoulder and observe the ice cut. If it appears to be shaved smooth all the way across, then the blade is shaving nicely. If rough spots appear, then the blade may need to be lowered a bit. There is a flat wheel attached to a shaft coming up from the middle of the conditioner. The wheel has a handle that sticks up off the outer rim. This is the blade height adjustor. Clockwise turns take the blade down to make adjustments to the shaving.

There are considerations to shaving depth, but I'll save that for a future article.

So, we're headed across the ice, the throttle is set, the conditioner down, the conveyors are running, and the blade is set. Time for water. Two water valves are controlled by shafts coming up to the driver's reach from the conditioner, on either side of the blade control. The lever closer to the driver is the resurfacing/fresh water. It gets turned on full blast at first to fill the pipes and get the water running. It is then adjusted to lay the proper amount of water, considering the amount being shaved off and the capacity to freeze at the moment. This can be effected by several environmental and operational factors, so I'll save it for another article. Suffice to say the water is adjusted.

Basically, you want to lay approximately the same amount of water as is being shaved off and to nicely lay down a coat. When you slow down in the corners, the water should be reduced a little to leave about the same amount per square foot. The water is gravity-fed. It is not under pressure and is not pumped out. The thing the driver pushes down vigorously is not pumping the water, as some believe.

That is called the "ice breaker." Down in the conditioner, where the horizontal conveyor tosses snow into the bottom intake port of the vertical conveyor, snow tends to collect and can jam up the operation. So, the ice breaker is there to knock that off. Drivers periodically push the ice breaker down to free up this collected snow. Basically, you can feel it in the machine and know that it needs to be done. Also when it is pushed down you can feel if there is resistance, indicating there is some accumulation going on, so it has to be pushed more vigorously.

Now the driver approaches the boards where the pattern starts, and initiates the "board brush" with the lever in front of the blade adjuster. The brush is hydraulic powered and works like a street sweeper, sweeping snow from the boards out and under the Zamboni so it can be collected by the conditioner.

The patter begins with the first lap around the arena. At the completion of the first lap, the board brush is retracted via the hydraulic control lever. Next the recirculating "wash water" valve is turned on. This releases water inside the conditioner, behind the blade but before the back wall of the conditioner. It is left to run for almost the length of the ice, to get enough in there for the pump to draw suction.

Before making the turn, the wash water pump is turned in with a switch on the dashboard. There is a hard suction line in the middle of the conditioner. The pump is on the right side of the conditioner. It draws a suction and pulls water from the conditioner and recycles it through a screen and back into the wash water tank. Then the wash water valve can be turned down to the desired level. Basically you want to be removing the same amount as is being pumped out, accounting for some that is left behind on the ice. Like the fresh water, the wash water might have to be adjusted for changes in speed.

Ideally, when slowing down to make the turns at the ends of the ice, the fresh water should be turned down and the blade should be raised a little; then the water is increased and the blade lowered after the turn. This is because this spot gets hit every time the Zamboni goes over it. During games, you don't want to flood the goalie crease with too much water; but if you back off the water and leave the blade, then you could shave too close to the paint. Thus the need to reduce water and cutting depth.

That's a whole lot of motion going on - espcially considering mascot activity, the maintenance guys moving the net and keeping the peg holes clear, etc. It gets kinda hairy in the turns.

Frankly, I usually leave the blade alone and just reduce water in the turns during games. There is enough depth that the three resurfacings won't get to the paint and it's best to just leave the blade in one place for consistency. And there is just too much going on. I'd rather leave the blade than run over somebody or something.

Making the last pass, the wash water valve is closed but the pump is left on. Eventually it pumps dry and makes noise, so it can then be turned off. As you approach the exit, the fresh water is turned off. As the front wheels hit the end of the ice, the conveyors are turned off. As the back wheels approach, the conditioner is lifted.

If there is only a small amount of snow to be shoveled, that indicates the cut when well and the Zamboni did not have trouble moving the snow. If there is a huge pile of snow, that's OK but the cut did not go perfectly. Maybe the ice was soft and got "muddy" with the water mixing with cut snow in the turns. Or maybe the conveyors did not keep up well because of RPM problems or harsh speed changes. It could be several things and it doesn't mean the ice is bad; it just means the snow removal part of the operation could have been better.

Note: the conditioner will not raise up if the conveyors are still running. They must be shut down first.

As you may have inferred, all these adjustments take a certain "feel" for the operation each and every time. How much to shave, how much water, RPM, engine sounds, pump sounds, etc. This is part of the "Zen" of icemaking. You can train, you can watch films, you can try to categorize every cause and effect; but there is no substitute for experience and knowning the feel, the sounds, the vibrations, etc. and then knowing what to do in order to give the best ice possible.

All that with professionals wanting perfect ice for their peak performance, with on-ice promotional activities going on, with a few thousand people watching, while the clock counts down to the start of the next period.

Stress? you be the judge.

Next up: The Zamboni HD-B control differences from the 500-series.

NOTE: Once again I invite any other Zamboni drivers out there to add their two cents to comments or send me an email. I don't claim to be the world's foremost expert; and I am largely self-taught over 20+ years of of-and-on experience. I can always learn and I enjoy Zamboni banter.


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