It is pretty clear that the best shape for a reciprocating piston is a cylinder. But has that stopped people trying other shapes? Oh no. Here is the strange world of square pistons.
THE ROOT ENGINE
|
| Left: Roots Square Piston Engine: the principle.
"The oblong square box,A, is the cylinder proper. b is a frame sliding freely in a horizontal direction by the force of the steam from the side ports, d,d. C is the inner rectangular piston, connected directly to the crank pin a, the shaft b, being central to the range of the moving pistons. The piston C receives steam from the top and bottom ports, d,d, within the frame B."
Very strange indeed.
From "Mechanical Movements, Devices and Appliances" by Gardner D Hiscox, published by Sampson Low, Marston & Co, 1899. The part of the caption that is in quotes is taken from this book.
|
 |
| Left: Roots Square Piston Engine: internal workings.
The large piston E moves horizontally. The smaller piston F moves vertically inside E.
T is the cover plate for the engine, incorporating a circular valve-box I, closed by a plate screwed over it. Steam is supplied via the valve K at the top, and passes to the valve-box by a passage not visible here. It enters the "cylinders" via ports G when they are uncovered by the valve X. The exhaust leaves through the same ports and enters the annular channel M and escapes through the passages shown dotted, which feed into a common exhaust duct.
The valve-plate X is fitted to an eccentric L on centre-pin D, and is carried round by a pin S on the end of the crank, so that it rolls around the inside of the circular valve-box, opening and closing the ports as it passes.
From Knights American Mechanical Dictionary, 1880.
|
THE DAKE SQUARE PISTON ENGINE
 |
| Left: Dake Square Piston Engine: 1899.
"Two rectangular pistons, one within the other, working at right angles in the outer piston. The inner piston is connected to the crank pin, and moves vertically. The outer piston moves horizontally in the case. The principal is similar to the Root Square Piston Engine."
Or to be more accurate, the principal looks spot-on identical.
From "Mechanical Movements, Devices and Appliances" by Gardner D Hiscox, published by Sampson Low, Marston & Co, 1899. The parts of the caption that is in quotes, are taken from this book.
|
This engine really was put into production, by the Dake Engine Company of Grand Haven, Michigan.
 |
| Left: Dake Square Piston Engine.
Against all the odds, some pictures of this extremely rare engine have been unearthed. This example belongs to Randy E. Schwerin of Iowa.
He says: "The first picture shows the "square piston" in place, and the internal surface of the cover with parts exposed. Proper clearance at this point is critical as this determines the end clearance of the piston itself. Therefore attention must be paid to the thickness of the gasket used."
From an article written for the US magazine Steam Traction by Randy E. Schwerin of Iowa in 1983. All attempts to contact Mr Schwerin or the editor of the magazine via the internet have failed, so I am showing these pictures as they are too precious to be lost. If anyone feels their copyright has been infringed then please let me know.
.
|
 |
| Left: Dake Square Piston Engine.
The Dake engine pictured is a 3.5 HP size. The photograph shows the opposite side of the engine with crank shaft and cover.
From the article by Randy E. Schwerin, 1983.
|
Randy Schwerin first encountered square pistons on a big Reeves traction engine, which used a small Dake engine as the power steering device. He says: "The engine steers the Reeves well at any pressure over 100 p.s.i. which says a lot for the power of it, as the Reeves weighs 27 tons. I would guess the little Dake to be 1.5 or 2 HP, with a 1/2 inch steam inlet and 3/4 inch exhaust. It weighs approximately 100 pounds.
"Basically, all that was required was a good cleaning to remove the surface rust that had accumulated on the internal parts and to resurface the controlling valve. Upon assembly and after hooking to live steam it ran smoothly and noiselessly with no dead centers, and reversing instantly upon changing the position of the control lever."
 |
| Left: Dake Square Piston Engine.
This shows the engine assembled.
From the article by Randy E. Schwerin, 1983.
|
 |
| Left: Dake Square Piston Engine.
This Dake engine belongs to Ed Richards of Saskatchewan, Canada.
He says "Steam at 100 psi is used to bear against a piston surface area 2"x7" and with a stroke of 2", (the engine) develops approximately 5 HP. This engine was used for pumping water into the tender of a large traction engine. With the piston being rectangular it requires careful shimming to achieve a satisfactory steam seal between the piston and the block."
From an article written for the US magazine Steam Traction by Ed Richards in 1973. As with the other pictures above, all attempts to contact Mr Richards or the editor of the magazine via the internet have failed, so I am showing these pictures as they are too precious to be lost. If anyone feels their copyright has been infringed then please let me know at once.
.
|
 |
| Left: Dake Square Piston Engine.
It seems pretty clear that sealing was an issue, with some critical assembly required to get a good seal. These engines appear to have only been used in small sizes and intermittently. The sealing losses in a large engine would probably have been excessive.
From the article by Ed Richards, 1973.
|
Dake engines were also used for hoisting. From an interview conducted in a study Michigan local history:
"The old Dake Engine Company, in its early days, that was known for making hoist
engines for ships, that, you know, the cargo hoist engine, and it was a square piston
engine that they built, and they still maintained parts for that for years after that because
those engines were so good and so reliable, all they needed were sometimes new pistons
or new rods or something like that..."
See here. (external link)
The Dake engine may have been unusual, but it did have some success. See below for details of the Dake Engine Company.
THE DAKE ENGINE COMPANY
The Company was founded in 1887.
A special feature in the The Evening Tribune, July, 1891 of Grand Haven, Michigan, refers to
"the celebrated Dake engine" and continues thus:
"DAKE ENGINE WORKS.
The most popular engine now in use for many classes of work is the Dake, invented by William F. Dake of this city, and together with other inventions of Mr. Dake, manufactured by the Dake engine Company. The plant has been in operation about four years and has a capital stock of $100,000. They turn out more than an engine a day upon an average the year around. The company has patents in this and other countries valued at $50,000. These engines are much more compact than any other engine made and may be reversed with lightning rapidity. They are adapted to all uses where steam is required, and the sales upon them are rapidly increasing. The officers of the company are Thomas Cairns, president, and James P. Armstead, secretary and treasurer. The company has a monthly pay-roll that contributes largely to the prosperity of Grand Haven."
See here. (external link)
Well, that states pretty plainly that the Dake engine was invented and patented by William F. Dake, though it is clearly not an impartial source. Did he copy Mr Root's design, or were they parallel developments?
According to The Eighth Annual Report of the Michigan Bureau of Labor and Industrial Statistics, the
Dake Engine Mf'g. Co. had 16 employees in 1890.
In 1940 the Dake Engine Company, was purchased by
Jacobson-Johnson-Sherwood. (external link)
