Author Topic: Design Evolution of the 20hp Stanley Engine.  (Read 1181 times)

Offline Elam Works

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Design Evolution of the 20hp Stanley Engine.
« on: September 21, 2019, 04:48:15 PM »
This article was written to document and as a guide to the design evolution of the Stanley Steamer 20hp engine (1905-26). It is posted here in case someone wants to build an authentic scale engine, they can decide what year engine they might like to model. Or, if taking a more freelance approach, what combination of features appeal most. You will note there are still gaps – such as 1914 & 1916 – where no information could be found on the engines. So this is a work in progress; this version below being revision 22. There are plenty of pictures of Stanley Steamers on the Internet, but not so many of the engines!


Design Evolution of the 20hp Stanley Engine.
Part 1 of 5

A Stanley owner once opined that the design of the engine changed about every fifth one built! An examination of engines undergoing overhaul revealed many, many evolutionary changes and a curiosity emerged to catalog them. The following timeline focuses solely on the 20hp engine, which had the longest run and greatest number of surviving examples to make observations on. Charlie Johnson, Mike May, Howard Johnson, Tom Marshall, and the Friends of the Auburn Heights Preserve contributed additional details, and their help is gratefully acknowledged. A few details and most of the help on the model numbers using the 20hp engine came from the Kit Foster book on Stanley Steamers. It must be recognized that a number of Stanley engine parts are interchangeable across the years, making present-day observations of survivors fraught with peril. In years past less concern was given towards authenticity, verses getting and Stanley engine going, keeping it running, and perhaps improving on the original. Even now many are modified to better suit the rigors of present day steam car tours. Original, undisturbed examples are now rare and prized. For brevity, the terms “presumed” and “probably” have been omitted but should be assumed before any definitive statement that follows! An earlier version of this article was published in the 2013 summer edition of the Auburn Heights Herald. Since then a few more details have come to light that have rounded out the picture. When finished (if ever?) it will serve as a resource for those that are restoring a 20hp and are sorting through a pile of parts trying to figure out which bits date to which year. So, in the beginning…

1905 The 20hp engine is introduced with the Model F. Bore and stroke is Ø3-5/8" x 5". The cylinder mounting ears are not flared in to cylinder trunk, and are particularly prone to fracture. Steam enters through the front end of the valve chest via the hollow front mounting stud. The exhaust manifold exits to the left. The main frame is of Ø3/4” rods, spaced 5" wide by 5" high (on centers). This is a “dry” engine, which, while enclosed in a sheet metal wrapper to keep out dust, is not designed to keep oil in or facilitate lubrication. The piston rod is Ø5/8", and the crosshead is poised between a pair of 5/8" bearing balls that oscillate back and forth along the crosshead guides. The connecting rods are 11-1/2" long (on centers) and use crowded 1/2” diameter balls loaded through a radial port. The port is sealed with a plug transfixed by a pinch bolt; despite appearances this does not allow adjustment for wear. The fork (wishbone) of the connecting rod has to be bent to install over the crosshead. The main crankshaft bearings are 3/4” diameter crowded ball, running in split outer housings separated by shims to effect adjustment. Adjustment is only fore and aft, but this is the direction of the most wear anyway. The crankshaft itself is Ø1-1/4”. In late 1905 or early 1906 counterweights were added to the cranks.  The reversing actuation lever is directly over the Stephenson links, on the centerline of the engine. It has an adjustable stop for setting cut-off in the forward direction, but no hook-up. The pump drive is indirect from the right crosshead, via a short link, a rocker arm, and then the pump reach rod. Models using the 20hp engine: F.

1906–1907 The Model H, with its successors the H-4 and H-5, utilize the Model F engine with higher gearing. Models using the 20hp engine. 1906: F, FX, H (some were 15hp), H1, H2, H3.1907: F, H, H3, H4, H5, J.

1908 The reversing actuation lever moved to the right side of the engine and incorporated, for the first time, a latch to “hook-up” the valve linkage into a shorter valve stroke for the purpose of more economic use of steam when the engine was not working hard. This changed steam admission from about 5/8 stroke down to 1/4 stroke. The pump drive is taken directly from right crosshead, via a curved pump reach rod with no links or rocker. Early in 1908 the cylinder mounting ears for the frame rods are reinforced by a small gusset. Late in the year they are fully flared into cylinder casting, much like subsequent Ø4 x 5 engines. Externally the valve chest on the top of the engine extends the full width, such that recesses are required for the mounting nuts (or was this just on the 10hp engines?) Presently I do not know if this was done when the small reinforcing ribs were added early in the year, or when the fully flared mounting lugs were introduced late in the year. Also a boss was added for steam admission to top of valve chest but seemingly not used. Models using the 20hp engine: F, H, H4 (none sold), H5.

(To be continued momentarily)

-Doug

Attachments:
1905 cylinder.jpg
Stanley 1907 20hp engine.jpg
1907 connecting rod.jpg
1907 crankshaft.jpg
1907 cylinder.jpg
1908 crosshead.jpg
1908 cylinder-early.jpg
1908 cylinder-late.jpg

Offline Elam Works

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #1 on: September 21, 2019, 04:49:29 PM »
Design Evolution of the 20hp Stanley Engine.
Part 2 of 5

1909 About June/July, the Model R and U (with higher gearing) were introduced to supersede the venerable Model F. The bore and stroke becomes Ø4 x 5 inches, and in general many of the engine components increased in size to suit. This remains the bore and stroke for all subsequent 20hp models. The cylinder casting is appreciably larger overall, with “C/1501” in raised, cast characters on the upper valve chest surface. Steam enters via a boss on the upper face of the steam chest; however, the front of chest is still tapped for a pipe thread to take a solid mounting stud. Main frame is now Ø7/8" rod, spaced 5-3/4" wide by 5-3/4" high (on centers). The piston rods increase to Ø11/16”. The new design is splash-lubricated; from the piston rod packing glands to the crankshaft is encased as one compartment. Introduction of the “wet” engine was a major improvement eliminating the need to oil all the moving parts in the crankcase by hand as was required in the “dry” engines of the earlier models. The drive gear increases from 7/8” wide to 1” wide. The crankshaft increases to Ø1-5/8”. The Model F hung on for part of the year using the ‘old’ 1908 engine. Models using the 20hp engine: F, H, J, R, U.

1910–1911 A cast aluminum bulkhead separates the crankcase motion compartment from the cylinder’s piston and valve stuffing glands so that leaking glands are less likely to contaminate lubrication. This adds length to the main frame, necessitating approximately 1” longer piston rods (not sure of exact length) and a connecting rod of 12-5/8”. A larger crosshead bearing ball of 3/4” appears about this time. The connecting rod now has a solid eye; no pinch bolt. The inner bearing race was of two halves allowing for assembly and adjustment. The outboard half was threaded onto the crankpin and screwed up against the inboard with shims betwixt to take up clearance. The crankpin nut locked (jammed) the inner race. Models using the 20hp engine. 1910: 70, 71. 1911: 70, 71, 72.

1912 An example of a 20hp connecting rod with crowded ball bearing big end but a detachable wishbone leg has been reported. A Stanley illustration of an engine attributed to 1911 shows the solid wishbone still in use, and the detachable leg in 1913. The detachable wishbone leg was introduced in this year on the 30hp. Other sources state the 20hp did not acquire the detachable wishbone leg until 1913 (see next). Improvements typically trickled down from the 20hp to the 10hp, and subsequently from the 30hp to the 20hp. Models using the 20hp engine: 73, 74, 75.

(To be continued momentarily)

-Doug

Attachments:
1909 cylinder.jpg
Stanley 1911 20hp engine.jpg
Stanley 1912 20hp engine.jpg
Stanley 1913 20hp engine.jpg
« Last Edit: September 21, 2019, 04:59:09 PM by Elam Works »

Offline Elam Works

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #2 on: September 21, 2019, 04:52:38 PM »
Design Evolution of the 20hp Stanley Engine.
Part 3 of 5

1913 Addition of a feed water heater necessitates a deeper flue alongside the engine. Consequently, the exhaust manifold now exits to the left and forward. This is the first year for the roller bearing 20hp engine, introduced on the 30hp the year before. Main bearings are Ø3/4" x 3/4" hollow rollers, rotating on pins that are riveted into side plates to form a caged assembly. Rollers run on a cylindrical inner race with a shallow lip toward the outboard end. The main bearing housings have a shallow groove (double lip). The connecting rod bearing design is caged like the mains, but of Ø5/8" x 5/8" rollers running in a shallow groove of a solid (not split) eye. No method of adjustment. Connecting rod has detachable fork leg to ease installation onto crosshead. Shims between the two cones set the wristpin clearance. The wristpin bolt threads into the inner half of the fork and is done up tight with a jam nut on the inside. Crosshead has recirculating Ø5/8" x 1/2" roller. Models using the 20hp engine: 76, 77, 78, 79.

1914 No information. Models using the 20hp engine: 710, 711, 712, 713. 714, 715.

1915 All 20hp models are now condensing cars; which started with the 714 & 715 models the previous year. Driving position moves to left-hand side of the car; so hook-up moves to the left side (of the engine) with the pedal(s). Therefore exhaust manifold now exits to right. Pumps are now driven off the rear axle, so there is no slot in the bulkhead for the pump rod to pass forward through. Pinch bolt returns to the connecting rod eye, which, with shims in the gap, allows the eye to be contracted and so take up clearance on the rollers. In a reversion to the adjustment method used on the 1912 and earlier engines, the wristpin bolt passes right through the wristpin cones with a nut and a jam nut on the outside (reversed from previous). How tight the bolt is sets the clearance. Crosshead guides are steel with convex surface, fitting the curve of the earlier ball style piston rod crosshead; no ball (or roller) or limit stop pegs. The crosshead has a matching concave surface. The main bearings and connecting rods change from caged to crowded rollers. Likely the extra cost and complexity of the cages was not warranted, when a simpler manufacturing solution of running the rollers in a deep groove (mains) or between guiding sidewalls (connecting rods) would suffice. For the main bearings, the rollers (still the same size) run in a deep groove of an inner race. One example has been seen with these rollers still drilled for cage pins; probably using up old inventory. The main bearing housing has a single lip towards the outboard side. Lugs appear on cylinder block casting for diagonal truss rods between cylinder and rear axle. Models using the 20hp engine: 720, 721, 722, 723.

1916 No information. Models using the 20hp engine: 725-5, 725-7, 726, 727, 728 (August).

(To be continued momentarily)

-Doug

Attachments:
Stanley 1913 20hp engine.jpg
1913 connecting rod.jpg
1913 crankshaft.jpg
1913 cylinder head.jpg
1913 cylinder.jpg
1913 main bearing.jpg
1913 roller crosshead with bronze guide conversion.jpg
Stanley 1915 20hp engine.jpg

Offline Elam Works

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #3 on: September 21, 2019, 04:54:43 PM »
Design Evolution of the 20hp Stanley Engine.
Part 4 of 5

1917 Crosshead guide remains steel, but is now concave. New piston rod crosshead with convex surface to match. Models using the 20hp engine: 728, 730, 731.

1918 With the model 735, the eccentrics change from 37º to 35º. Previous eccentrics marked with a center punch dot to the outside to aid correct refitting. Later eccentric stamped (sometimes!) “35º” on the outside face. Piston rods projects 1/4" through the piston (so piston rod is probably longer) and locked with a jam nut. I am not sure when this started (after 1913), but seems to have showed up with the 735 models. There is a recess in the cylinder head to accommodate the nut, so the head now has a large central boss to accommodate this recess. This would be visible externally. Previously the end of the piston rod was flush with the piston and peened to lock it to the thread, and the head had just the cross rib that you hammered on (!) to tighten/loosen the head. Crosshead guides are now bronze castings, concave in shape. After the 735 model, eccentric timing reverted to previous value. Some sources give this as 40º, not 37º. I did not check eccentric angles on earlier engines, so not sure. Seemingly undisturbed 740 and SV engines have been seen with the (marked) 35º eccentrics so after 1918 they may have not reverted to the earlier eccentric angle after all. There are likely many different slide valves with different length laps used over the years, so beware! Models using the 20hp engine: 735, 736, 735D (September).

1919–May 1922 Hardened slide valves, requiring a change in cylinder oil. A 1919 service bulletin states because of this the new oil is not compatible with earlier engines, and vice-versa. About this time the markings on the cylinder block change. The date cast appears: “2 23 20” (M D Y), and the foundry trademark of “MFCO” within a diamond, and a (part?) number 101. Models using the 20hp engine. 1919-20: 735A, 735B, 735C, 735D. 1921: ditto, plus 735E, 735F.

(To be continued momentarily)

-Doug

Attachments:
1918 connecting rod.jpg
1918 crank.jpg
1918 crankshaft roller.jpg
1918 crosshead with bronze guide conversion.jpg
1918 cylinder head.jpg
1918 cylinder.jpg
Stanley 1918 20hp engine.jpg

Offline Elam Works

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #4 on: September 21, 2019, 04:57:01 PM »
Design Evolution of the 20hp Stanley Engine.
Part 5 of 5

May 1922–1924 740 model introduced in May 1922 and probably superseding the 735 in production with negligible model overlap. Casting date on example cylinder block: “8 15 22”, but no ‘part number’ and no diamond foundry trademark. Tie rods between the upper and lower engine frame cross members are double-nutted to rigidly fix distance. Previously tie rods only stopped the upper and lower frame rods from spreading apart in the area of the crosshead guides. Engine number now (additionally?) stamped on a frame rod rather than the upper rear cross member casting. Models using the 20hp engine. 1922: 740A, 740B, 740D, 740E, 740F. 1923: ditto, plus 470G. 1924: 740A, 740B, 740D, 740E, 740G, 750A, 750B, 750D, 750G.

1925–1926 Introduction of the “SV” engine. Engine has cast aluminum sides to motion chamber (engine crankcase) with pressed steel upper and lower panels for a boxlike construction. No trace of casting number on cylinder. Forward mounting lug on the cylinder reinforced with large boss and gussets. Diagonal tie rod lugs still present on the sides of the cylinder block, but not drilled and tapped for tie rods. Semi-elliptic springs at the rear were introduced in 1924, negating need for perch poles and possibly the need for a braced engine. Or it may be that the box construction and larger diameter frame rods (between cylinder and main bearings) sufficed for rigidity. Or perhaps the larger engine case of the SV simply got in the way of installing the tie rods. Exhaust manifold exits to the left. Main bearings are commercial ball bearing units; main bearing housings are consequently not split. Helical final drive gear (many replaced with earlier crank assemblies using the spur gear). Cylindrical trunk guides integral with cast aluminum baffle. The engine number is stamped on the baffle where the upper left frame rod passes through. The engine rods are about Ø1-1/8” (?) from the cylinder to the main bearings, with an even larger diameter sleeve between the bulkhead and the cylinder block. The frame rods revert to the old Ø7/8 through the main bearings and out through the rear axle. Connecting rods have a solid eye and crowded rollers; a regression with no means of adjustment. Small end eye fitted with a bronze bush for a conventional gudgeon pin in a cast iron crosshead “piston”. Models using the 20hp engine. 1926: SV-252-A, SV252-G. 1927: SV262-A, SV-262-G.

-Doug

Attachments:
1924 cylinder.jpg
1925 connecting rod.jpg
1925 crankshaft.jpg
1925 crosshead-1.jpg
1925 crosshead-2.jpg
Stanley 1924 20hp engine.jpg
Stanley 1925 SV engine-1.jpg
Stanley 1925 SV engine-2.jpg

Online crueby

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #5 on: September 21, 2019, 09:38:03 PM »
Wow, thanks Doug!!  Printing this one out to sit out on the porch and study, love it!


 :ThumbsUp: :cheers:

Offline Steamer5

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #6 on: September 22, 2019, 04:19:31 AM »
 :drinking-41: :drinking-41:

WOO HOO!

Thanks Doug! I know a couple of people who will enjoy reading this!

Cheers Kerrin
Get excited and make something!

Offline gbritnell

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #7 on: September 22, 2019, 12:35:01 PM »
Thanks so much Doug,
Some very interesting reading.
gbritnell
Talent unshared is talent wasted.

Online Roger B

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #8 on: September 22, 2019, 06:21:33 PM »
Doug, although I am not a 'steam' person I have to thank you for posting so much carefully collected information for others to benefit from  :ThumbsUp:  :ThumbsUp:  :wine1:
Best regards

Roger

Online crueby

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #9 on: September 22, 2019, 06:36:56 PM »
Got it printed out, nice weather today to take it out on the porch to read. In glancing through the pictures, there is quite a lot of difference through the years.
 :ThumbsUp: :ThumbsUp: :ThumbsUp:

Offline b.lindsey

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #10 on: September 22, 2019, 07:40:00 PM »
Interesting reading. Thanks so much Doug!!

Bill

Offline Elam Works

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Re: Design Evolution of the 20hp Stanley Engine.
« Reply #11 on: September 22, 2019, 09:54:13 PM »
Quote from: crubey
...there is quite a lot of difference through the years.

Unfortunately, they could not evolve enough to overcome the convenience of Charles Kettering's electric starter when combined with internal combustion engines!

Many of the changes were to make the engine more robust, yet their adherence to the four bar frame to the end meant for a rather limber engine. This was not such a big problem early on with the lower boiler pressures and ball slide cross heads. But with the change to rollers and higher pressure, the bearings just could not tolerate the angular motion. Under load, the cylinder block can be seen twisting clockwise and counterclockwise. Bearings fractured and frame rods broke. Probably one of the reasons they went to plain bearing cross slides. The frame rods are further weakened by full length threads and cross pinning to reduce the already overloaded cross sectional area. Folks touring have come up with various ways to reinforce and stiffen the frame.

-Doug

 

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