Fitz Water Wheels
The wood overshoot still survives as an active competitor of the small turbine ill some parts of the country. On a light stream, a well made wood wheel will often give better results than a turbine, but it always falls far short of getting the full possible power front the water.
Wood is not a fit material to use in building a water wheel. A high efficiency wheel must be made of metal. Wood overshoots have been built for centuries; hut up until the advent of the Fitz, an efficiency of 75% was considered the limit for an overshoot wheel of any kind. Mighty few wood wheels ever approach that efficiency today.
The buckets of a wood wheel cannot be shaped to a suitable curve to receive and discharge the water properly. A wood wheel is invariably out of balance and- its jerky motion is destructive to good results front the machinery it operates. The constant swelling and drying of the wood soon causes all parts to get loose: the buckets leak: and a considerable proportion of the energy is wasted.
In a steel wheel, the buckets can readily be shaped to suit the design required. The 'Fitz steel bucket is shaped so as to receive the water at the crown of the wheel with the least possible shock. It retains the water to a point just a little above the level of the tail race. In other words, the water gets to work on a Fitz wheel at least three buckets earlier than it does on other wheels, and it stays on the wheel from three to ten buckets longer, depending upon the diameter of the wheel.
A wood wheel gets no benefit from the head of water over the top of the wheel. In order to put the-water into the thick, straight, wood buckets, the chute is generally-slanted a good deal and the water is allowed to "drop" on to the wheel in the Manner illustrated on page 31.
The water consequently strikes the wheel at an ineffective angle and its energy is dissipated in shock, instead of being communicated to the wheel.
This loss is more serious than the casual observer would suppose. In the case of a 14 ft. diameter water wheel, for instance, the total head is usually at least 16 or 16 ½ft. Two feet of that total head are in the depth of the water in the forebay over the, top of the wheel. If the water wheel does not utilize that 2 ft. of head (and a wood wheel never can), then it is wasting 12 or 12 ½ % of the power at this point 'alone.
The illustration of the steel wheel on this page, or better yet, the larger cut on page 18 will show' clearly how the water is applied to a Fitz Wheel. Our steel chute is set nearly level. The water glides over the smooth steel with very little loss by friction, and shoots into the steel buckets in a direction just tangent to the crown of the wheel. Its energy is thus applied to the wheel at the most effective angle. The buckets are given just the right curve to enable them to receive the water with the least possible waste of power by "shock." Study the photo’s on pages 31 showing Fitz Wheels, photographed while running, and compare these wheels with the splashing, sloppy, leaky wood wheels to be found everywhere.
(Page 31 Picture) Snap-shot Photo of 12ft. diameter by 9ft, face Fitz Steel Overshoot Water Wheel, running at full speed and driving mill of Bruce Bros., at Gormeley, Ontario, Canada. Please note the absence of splashing water. This is one of the "differences" that marks the superiority of the Fitz over the old-fashioned overshoot wheel. In installing this wheel, the concrete penstock which held the former turbine was, used as shown. The water is brought to the penstock thru a round steel flume laid right on the ground. In the concrete penstock the water rises up to the same level as the water in the dam and is carried out to the Overshoot by means of a short wood forebay built out to receive our iron gate and chute. This extension in other cases. is frequently made of iron or even of concrete.
Snap-shot Photo of Fitz Water Wheel running in exposed location in Northern New York. This is not a fair test, since the wheel should be installed inside of building in such climates and the water should be brought to the wheel in a water-tight flume or steel tank. However, in spite of the old-style leaky wood forebay, and the utter lack of protection from weather, please note the failure of any ice to cling to the water wheel itself.
In cold weather, ice gathers on the arms and shaft of a wood Wheel, putting it to a terrible strain and often causing it to stop running. Every one who has attempted to cut ice from a wood wheel knows what a difficult and dangerous job it is and how frequently it must be clone in a severe winter. Wood is a non-conductor of heat and all the water which is running over the wheel is usually warmer than the freezing point, the wood wheel will gather ice rapidly along its housings and arms. The water splashing over the sides of the wheel freezes on the shaft alls. The ice freezes right into the pores of the water-soaked wood, and is very difficult to dislodge.
Fitz Water Wheel in operation at Marlboro Mills, Marlboro, N, Y., on State Highway Route 9W. Note water-tight Fitz Steel Flume and Forebay Box, in connection with freedom from ice.
Ice does not affect the steel wheel, because, steel is a good conductor of heat. The steel buckets readily assume the same temperature as the running water'• and they communicate that temperature to the housings and soling, so that no ice will gather on the wheel while running. Even if, thru a leaky forebay, sonic ice is allowed to form on the wheel standing idle at night that ice will wash off the wheel when the water is turned on in the morning. Ice cannot get into the pores of the steel, and hence has no opportunity to cling to it like it does to wood.
In very cold countries, we house the wheel in, so as to protect it from the cold winds. The friction of the running water liberates a certain amount of heat in the wheel room and prevents any trouble from anchor ice. The freedom of the Fitz Wheel from ice of all kinds is one of its strongest points. Neither the turbine nor the impulse wheel can compare with it, in its immunity from trouble with slush ice or frazil ice.
Our wheels are in most successful use all along our extreme northern border and in many provinces of Canada, in situations where a wood wheel would be impossible, and where turbines have proven very trouble some on account of ice.
About six inches of the fall is usually wasted in the slant of a wood chute and the clearance between the floor of the chute and the inside of the buckets. This space is all saved in a steel wheel. Several inches can be frequently gained at the bottom of the wheel for the reason that the steel buckets require less clearance from the tail race. We build all our wheels to suit the locations where they are to go and are glad to advise our customers as to the proper size wheel to fill their individual requirements.
A wood wheel is completely paralyzed by a little back-water. Our smooth steel buckets create much less friction than wood buckets when wading in back-water. They are ventilated so as to avoid creating a vacuum when discharging the water, and consequently do not suck up water as a wood wheel does. We rate our wheels at the power they develop with buckets filled only 4 full. When it is necessary for them to run in back-water, the buckets can be filled up full.
One of our 17ft. diameter wheels driving the pumping plant of the Hanover & McSherrystown Water Co., near our town, frequently wades in back-water to a depth of six feet without affecting its work. Water is plentiful at such times and more can be used on the wheel to overcome the loss of head.
A water-soaked wood wheel weighs three times as much as a steel wheel and the friction of the bearings is many times greater. Standing idle for one day, the wood wheel absorbs water on one side and is then out of balance. Its jerky motion wastes both water and power. No machinery requiring a smooth, even speed can be driven successfully with it. It is impossible for a Fitz Wheel to get out of balance. It runs so smoothly that its speed can readily be controlled by the Fitz Automatic Water Wheel Governor.
The life of a wood wheel is short, not much over ten years as a rule. The old time wood wheels lasted longer, but the old time material is no longer available, and the old-time millwright is fast disappearing. A Fitz Wheel will outlast a number of wood wheels. The metal wheels we built in 1852, at our old shops at Martinsburg. W. Va., are still in active service today.
The one excuse that a wood wheel has for existence today is its supposed cheapness in first cost. Even that claim is frequently without foundation. The manifold advantages of steel wheels in every other respect will far outweigh any difference in cost, to the man who is looking for actual value.From the Library of Robert Vitale (Fitz Bulletin #70)