A little something about Jensen: Click Here
Engines in this Collection:
(click hyperlink to jump to that engine type)
Approx. Dates: Model
late 1930's...................# 5 "Riveted Boiler" Oscillating engine
mid-1940's..................#20 "Big Power Plant" w/horseshoe cast iron generator
late 1930's..................#25 "Riveted Boiler" non-reversing type engine
Dec. 2006....................#51 (replica) power plant built up from a 1967 era Jensen 50
2008 ?.........................#95G Turbine engine paired with a #15 BL generator
2008 ?.........................Standalone 3" Jensen Boiler to steam orphan engines
A little about Jensen Engines and Accessories
There are a miriad of makers long since gone out of business, and a few still around, but there is just something about Jensen's "Abrams Tank" demeanor that draws me to them.
Jensen is still very much in business at their original Jeannette, PA, U.S.A. location, and although "old world" in their manufacturing processes, they have a state of the art Jensen website worth a leisurely visit to view their currently made models, tour their one of a kind shop, see how they make their engines and meet the handful of people who ARE Jensen today.
Their museum section Jensen Online museum for models dating back to the early 1930's is an excellent source for Jensen identification, and much of my information ties back to it. I have also added in Aug. 2010, a specific tab to this website with a chronology of Jensen models and an extensive variety section covering #10's, 20's, 25's, 50's and 51's put together by two leading collectors.
If you need parts for new or old models, Jensen generally has them and they are just a phone call away at: 1-800-525-5245
Three key Jensen videos well worth watching:
First is a video made several years ago by a PA TV station, showing the people and facility where every Jensen is made:
Second is another superb video of the Jensen factory done by www.ministeam.com in Sept. 2011:
Third, is a 2015 historically significant video by fellow steamer "Reddrryder", documenting the fact that a Jensen 50 engine and generator combination produced the first electricity from nuclear heated steam in 1948 at the Oak Ridge Laboratories in Tennessee.
Gil made an 800 mile trek to the Oak Ridge facility to make this video. The Jensen 50/generator combo is still on display there. Lots of behind the scenes access:
- longer boiler...earlier ones were shorter
- tall/longer smooth black firebox...earlier ones were shorter and squatter
- riveted boiler (10 per end) with soldered in bushings throughout
- riveted boiler straps vs. nuts and bolts
- early design external sight glass and steam dome, with solid vs. hollow steam screws
- straight black dowel handles...bit longer than later ones
- nickel plated cast iron flywheel- wide top to the pressure valve
- cloth cord exits chimney base via a flared hole (before Heyco connectors) and chimney base has screwed on cup that supports the chimney
- robins egg blue cast iron engine base with cast in horseshoe shape beneath flywheel...later versions squared off the recess and were painted a darker blue
As with the other riveted, 1930's vintage Jensens in this collection, this engine has a black painted, brass chimney.
In the forties Jensen transitioned this to nickel plated brass, but the painted version is correct for this engine.
So, how well does it run??....Sweet, check out the video below.
To say I've been looking for one of these for "awhile", would be an understatement.
This engine came to my collection in the same way as most, via eBay, but with a bit of a twist this time. As listed it was missing the standalone lamp post and the generator electrical contact setup seen here. As a result it did not meet the seller's reserve price and went unsold.
I then contacted the owner and negotiated a sale, taking a chance I could find or make suitable replacements for the missing parts. Upon receipt, I did hesitate for 6 months to refinish this like my other robins egg blue/riveted boiler pieces, wondering if I should retain it in it's original condition, engine rust and all.
In the end my OCD tendancy won out and I'm glad it did.
This engine has many of the exact same dating features noted on the late 1930's Jensen 5 that preceeds it above...even the wood looked like it was of the same grain! I would therefore estimate the date of this engine at 1938-39.
It would NOT have been earlier than 1938 as an example in the Jensen online museum dated 1937 used a more complicated electrical contact setup that appeared to be made of Bakelite. Mr. Jensen simplified this a bit a year later to what you see here. I thank steam friend Gil for some photos to go by to replicate the Masonite/brass contact block...it now mimics yours exactly and works perfectly.
This engine got a complete restoration as well as a new made stand alone lamp, new painted brass chimney patterned off the original, and a new generator contact block. I finished it up in July 2008 and I'm once again impressed with the design genius that went into this engine by Mr. Jensen. It is truly an elegant piece yet among the most efficient he ever built.
The straight line generator configuration common to the early Jensen 10's, results in less waste energy than a separate generator connected by belt, hence the lamp glows very bright on this design.
The boiler's nickel finish and general condition is about the best of all my Jensens. Their earliest boilers and engines benefited from superior metal preparation (burnishing) and what seems to be multiple layers of plating.
This caliber of metal preparation could probably not be sustained during or after WWII without pricing Jensen out of the market. It is nice to find one however, nearly 70 years later!!
I discovered an oddity I've not seen before. The firebox on this piece was designed so the boiler strap retention screws threaded directly into the firebox lip itself. This is the first example I have come across like this...all others were either nut and bolt, or riveted. It was so simple to re-attach the boiler straps on this one, that it made me wonder why this strap attachment method was tried and abandoned?? Perhaps stripping out the holes became a problem?
I'm pleased that this particular engine did not get Mrs. Jensen's COMPLETE paint job...where she also painted the copper windings inside the generator as seen on many examples. The windings on this generator (as seen below), were left unpainted, for which I'm grateful!!
Like the Jensen 20 and 50 further down the website, I took an extra liberty in this restoration...I uncovered and polished the nickel plated screws on the generator's sides which are always painted over. I know this was not an original feature, but it should have been, it simply looks better !
This plant runs like a champ as can be seen in the following video. It was well worth taking a gamble on buying this engine, I could not be happier.
In early May 2008 I experienced a "Perfect Wave" so to speak in the world of eBay auctions. My find was what Jensen originally called their #20 Big Power Plant". It featured a non-reversing 20 sized engine with 3 inch boiler, driving a tough to find standalone horseshoe magnet style generator all mounted on a solid wood base. The auction BIN price was right and in 20 seconds I was the winner.
I was the first to view that auction and friend Gil was #2...but by the time he hit the BIN button, it was sold. I've never pulled that off before and was further amazed when Gil called me moments later laughing out loud that he missed it by seconds.
The first picture below is how it looks now AFTER full restoration.
This BEFORE picture is how it looked on eBay.
As described in the auction it needed a chimney, chimney stand, heater and cord, but otherwise was in decent shape. Upon receipt I was delighted to find that although the heater was dead, it was in the company of the chimney stand, something I figured I was going to have to otherwise make by hand.
I gave this one the "full meal deal"...complete restoration from top to bottom.
I have made a number of Jensen decals, but this was my first UL sticker and I was pleased with how it turned out. It might seem a minor thing, but such stickers are like ID labels to me, the engine isn't complete without one.
The nickel polished up nicely and was set off with new high temp firebox paint and my standard blue tractor paint for the cast iron surfaces. I swear Jensen used such tractor paint originally...though mine is a few coats thicker than factory original!
The blanket heater was replaced with a new one from Jensen and the tired looking cord was also replaced with a new, period correct cloth covered type.
flywheel and engine are precision works of art on this piece. They
polished up nicely to look the part and perform flawlessly...early
Jensen nickel plating was amongst the best they have ever offered.
Being a mid-'40's version of the #20, this engine was made before Jensen began adding the Stephenson's Reversing Linkage as seen on younger versions. It goes one direction and one direction only...but does so quite elegantly!
horseshoe style standalone generator is one of the earliest generator
versions Jensen produced and in my opinion, the strongest version
measured by light output.
The horseshoe variety just captures my heart for best of show vs. any other generator type out there including other Jensens. I was delighted to learn that these early horseshoe type generators also featured a machined brass pulley with nickel plating...all Jensen pulley's since are of the aluminum variety.
All things considered I feel very fortunate to have obtained this engine and been able to spruce it up for another 50 years of enjoyment by me and the owners that will follow me.
It runs beautifully as can be seen in the following video.
CLICK HERE for an instant video
Here is a soul mate to the 1937 Riveted Boiler 4-Bolt shown just before this one.
It is similar in many ways to the 4-Bolt, though it demonstrates key transitional changes that would come to be standard in model #'s 5, 10 and 25 down the road.
This engine bears a smaller cylinder, taller/longer firebox, longer riveted boiler, cloth cord exiting the rear of the chimney base, solid wood base, robins egg blue engine frame, mounting lugs externally molded into the cast iron engine frame and a decal.
This version of the 25 had an outside cylinder diameter considerably smaller than the 4- bolt version which sported an excessive 1/4 inch thick cylinder wall that the 4 cylinder end cap bolts screwed into.
In actuality the cylinder bore and stroke are the same for both versions, at 1/2 inch and 5/8 inch respectively. While wall thickness was reduced compared to the 4-bolt, Jensen has maintained this same cylinder wall thickness for almost 70 years and exceeds all similar sized competitor engines by 2-3 X.
As with all the riveted style Jensen's from the 1930's, this one includes a black painted brass chimney, a feature that was replaced with nickel plated brass in the forties, but is correct for engines from the late thirties.
It also bears a couple of unique features eliminated soon after. First it has a rare, square style steam valve and NO Stephenson's Reversing Linkage, a nice feature added to later model #25's. All things considered, this piece possibly dates between 1937 and 1939.
Closeup of the highly coveted rivets (called eschucheon pins by Mr. Jensen). These are found only on the 1930's and early '40's Jensen engines before the advent of stronger silver soldering which made them unnecessary for strength.
This piece was from the collection of a former sales manager of Jensen and had been restored previously. However, the robins egg blue color didn't seem quite right to me and the firebox had been sandblasted at some time, leaving a somewhat rough finish under the paint.
So it was an easy decision to re-do it to my personal satisfaction.
Although I fabricated the decal on this one as I did for the 4-Bolt, both originally did have decals in poor condition. Decals were how Jensen labeled their engines at the time...model numbers were not applied until the brass ID tags came in years later.
At this close of a photo, you can tell from the grain of the wood that this (and the 4-Bolt) received a furniture smooth finish somewhat nicer than they came from the factory.
I'm partial to perfect !!!
In 2006 I was fortunate to be one of the first buyers of Jensen's new model 95G turbine power plant featuring a new design of turbine by Karsten Gintschel of Germany. I got serial #3 signed by Mr. Jensen. I kept that plant for several years but ultimately sold it on as I was not completely satisfied with the plant's ability to make enough steam to keep the turbine/generator spinning at optimum level.
Ever since selling my original 95G I sort of regretted it, as I truly loved the turbine...it just needed more steam IMO to operate at it's best. I then realized I could tap the steam from my Jensen 51 replica with it's 5" x 10" boiler heated with 1620 watts.
In 2011, steam friend John sold me his 95G which was in like new condition, probably 2008 vintage. I didn't fire it upon receipt, instead I disassembled it and opted to make it into two projects I have had a mind to do for some time. This first project was a standalone turbine/generator to be powered from my 51R.
Here is the 95G as received from John in virtually factory new condition.
Here is how it looks today less boiler/firebox (Oct. 2011)
What you see above is the turbine from the 95G mounted on a nice custom made walnut wood base and lashed to Jensen's #15BL (ball bearing) generator. The #15BL runs with a bit less resistance than a stock 15 and as I had an example of the ball bearing kind, I put it to work.
Next photo shows the opposite side of this setup
Visible above are the mods incorporated to improve performance and looks IMO.
1) Visible between the turbine and generator is a small steam "shield" I made to block the steam from wetting down the generator which it tends to do on the 95G. That simple bit of aluminum blocks 100% of the condensate that would otherwise tend to drown the generator!
2) A switch has been added behind the generator. This lets the turbine get up to speed before adding the extra load of illuminating the bulb or allows the turbine to spin even faster without any bulb load.
3) The stock generator lamp bulb Jensen uses on a 95G is a lower voltage/amperage type called a #352X. Given my setup puts out more voltage and amperage, I was able to go with a higher voltage/amperage bulb called a #502 which puts out more light without burning out. The bulb's threads were also better concealed by adding a chrome washer and O ring which seals the electrical contacts from moisture.
4) The steam line was reconfigured to enter from the walnut base and I swapped in an earlier "skinny snowman" type wood handle on the steam valve.
5) I had some nickel plated screws, so used those on the bases of the turbine and generator...just a bit nicer than stock.
The photo below is a closeup of the brass geared 10 to 1 reduction/transmission that is a stock part of the turbine. The gear train enables the high speed but low torque of the turbine to supply slower speed but higher torque needed by the generator. Those gears, flywheel and main shaft driving the flywheel ride in six ball bearing races reducing resistance to a minimum.
The shortened condensate drain is seen on the lower left. The reworked steam line now enters at the lower right with steam valve above it.
At the end of the day...is this setup any better than what issues stock as a 95G from Jensen? In my opinion, absolutely, this thing is a screamer tethered to 30 PSI of constant steam pressure, and the generator operates at an optimal level.
As a followup to my Jensen turbine/generator setup noted in the previous paragraph, I took the remainder of a Jensen 95G plant and used the boiler/firebox to create a standalone steam source for orphan (no boiler of their own) engines in my collection.
The salmon firebox/stack color was replaced with a black paintjob as quickly as I could get it done...I am NOT a fan of Jensen's salmon pink!
The 3 inch x 6 inch boiler is heated electrically by an internal 660 Watt immersion rod heater which gets up to steam and pressure quickly and maintains it there for all engines I have tried except my turbines (which are tethered to my Jensen 51 replica's boiler for ample steam and pressure).
A pressure gauge was adapted to fit in the front boiler top hole previously used for the steamline. Steamline was moved to the rear most boiler hole and feeds a steam valve mounted lowdown to the rear. Here steam will be tapped for any engine desired. Safety valve was "uprated" with greater spring tension, to consistently give 25 PSI vs. typical 12-20 PSI of stock safety valve.
Simple project with a very useful outcome, all mounted on a nice routered walnut base. Here is a video of this boiler feeding a Stuart S-50 while electric input has been throttled down with a variac to allow low pressure steaming in this case.
0-6 volt generators with lamp fixtures have been with the Jensen line since the mid 1930's in one version or another...all under the general "Model 15" name. Though sold as 0-6 volt, my personal experience is that at the speeds of Jensens they are lashed to, it's more reasonable to expect 3 volts on average.
I've currently got a collection of FIVE of these generators, each unique in it's own way. Here's a family photo, then each will be described further below.
OK...I know the above photo shows SIX generators, as I have since traded the 1951 round magnet version for another engine. It was a rare beast, but I'm happy with the trade.
My oldest Model 15 is a one piece Horseshoe Magnet style first introduced in the late 1930's in a robins egg blue color and later dark blue. This style remained in the product line til 1950. This specific example is from the mid 1940's and it's borrowed off my Jensen Model 20 Big Power Plant of that era.
The horseshoe style generator is probably the strongest I own in terms of light output for a given speed...a very well made and attractive generator.
The cast iron based generator in dark blue paint introduced in 1952 utilized a new design 3 piece magnet replacing prior versions. The 3 piece magnet in and of itself has been in the Jensen line from 1952 to present, though the base changed along the way.
This cast iron based model remained in the Jensen line from the early 1950's into the mid 1980's. I believe Jensen transitioned from blue to teal green painted cast bases in the mid-1960's. Here's two photos of the blue version and teal version...identical except for paint color.
In the the mid 1980's, Jensen switched from the cast based version of the Model 15 to a pressed aluminum base version pictured immediately below.
The aluminum based type works a little better because of a separate brass contact for grounding vs. the cast iron type that depended on the axle to journal contact for it's ground. This model is the surviving Model 15 in Jensen's lineup.
One additional version of the aluminum based Model 15 was offered by Jensen from 1995-2005. The Model 15BL was likewise an aluminum based version, though the aluminum was blue in color and featured a pair of ball bearing races supporting each end of the axle, these generators are indeed very smooth operators.
The BL versions had one additional feature, an extra pulley and extra steps on both pulleys...enabling the generator to function as a line shaft while in use. Unfortunately, they proved to be very difficult to manufacture and were discontinued in 2005.
One other Jensen Generator version was made available in very small quantities as an AC/DC version. This was offered as part of the Model 51 Power Plant and the Model 15D, an accessory set sold in the early 1990's as a small setup with line shaft, little motor and lamp post to demonstrate with.
I believe there are only 3 or 4 of these known to exist in collector hands. An actual stand alone model 15D is shown in the Jensen Online museum. If you find one, please contact me discretely and I'm sure we can come to an understanding !
All of the examples above work beautifully and use a #14 bulb readily available from Radio Shack.