Jensen

Jeanette, PA

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Jensen is the oldest US model steam manufacturer, and the only one still in business. The history of Jensen is told far better on their site, so I won't bother to repeat it here.

While the earlier Jensens did not feature the ornate finish of some of the finer Nuremburg models, they have a simple elegance of their own. As befits Tom Jensen’s native country – Denmark – his engines are simple, strong, easy to maintain, and very durable.

I love finding old Jensen engines, because they are almost always in running condition, or easily returned to running condition. Replace the sight glass seals, sometimes the power cord, a little oil in the cylinder, and they come right back to life. My real love is the old wood base Jensens. Still relatively inexpensive, except for the riveted boiler examples, which are astronomically priced right now, but they have such character. Note the trio of riveted boiler 25’s below –  almost 70 years old, all are strong runners, and all needed only minimal maintenance to achieve running status.

A word of caution on running the old electric Jensens... the heater on the old wood base Jensens is NOT sealed. Spilling water down the side of the boiler while filling it can (but not necessarily will) set up a shock hazard. I strongly recommend that the old Jensens only be plugged into a GFCI circuit when running, the ground fault breaker will detect a short to ground and disconnect. Most modern bathrooms and kitchens have GFCI plugs on the outlets near sinks (the Code calls for it) these will be the plugs with a test button and a warning light in the middle.

Jensen 10

The classic Jensen, with the dynamo built onto the crankshaft. A favorite of Jensen collectors. There is something about the look of a 10 that draws you to it. A very handsome engine.

Riveted Boiler/Robin's Egg Blue 10
The Jensen 10 is one of the most desirable of the older Jensens, and the riveted boiler/robin's egg blue 10 is without a doubt the most sought after of the 10's. If you see one for sale, don't ask the price, just throw your checkbook and hope for the best.
The riveted boiler and robins' egg blue date this one, like the three 25's below, to 1936 or 1937.

In running condition. After replacing the seals, this old beauty came right back to life. I just love Jensens, you can put them through hell and they still come out ready to run.
In as received condition. All there, but not a pretty sight. After three evenings of cleaning. I'm not completely satisfied, but it's definitely looking better.
More shots of the same. Mrs. Jensen wasn't stingy with the paint - all of the robins' egg blue 10's have the armature painted.

Note the closeup of the dynamo. Unlike later 10's and model 15 generators, it has two contacts instead of one, which are anchored on a piece of pegboard, itself anchored to the wood base with a single long wood screw. No eyelets to attach the wire to the contacts, the wires were stripped and looped around the screws - most likely by Tom Sr. himself.
Another before/after comparison.
Late 1940's Single Piece Magnet 10
A terrific running engine. I just love to fire this one up and watch it run. One of my favorites to demonstrate for kids.

One can see some of the evolution of the model 10 in comparing these two models. The lamp post has moved from being standalone and screwed into the wood, to being mounted directly on the cast iron base. The two brushes on the dynamo have given way to a single brush, with the second contact being the axle. Armature winding looks to be a bit more precise. And the single brush is secured directly to the base, rather than being attached to a piece of pegboard and wedged in place. Improvement where it was needed, but the boiler and cylinder have been left alone (except for the omission of the rivets, darn it) as these already worked to perfection.

I have to tell this story... I was demo'ing this engine to my daughter's 3rd grade class as an example of how electricity is generated. The kids got a big kick out of the whistle. I then pointed out to the children that the electricy in the classroom was also being made by a steam engine - from the Tyrone #2 power plant that is located about 10 miles from the school, which is a coal fired steam plant. At that point, one little boy put up his hand and asked - does it have a whistle?

Jensen 55
2 cylinder model. As the tag does not show a zip code, this engine was built before 1964, when zip codes came into use.

A nice engine, but at best a languid runner.

Jensen 25

 

These three models are among the rarer Jensen 25's. They feature the early riveted boiler construction used by Tom Sr. in the 1930's. That riveting was made possible by a special drilling machine designed by Tom to drill all of the holes in the boiler and endcap in one operation.
I'm not sure when Jensen discontinued riveting, I believe it was in the mid 1940's. A pity, the rivets give the old Jensens a lot of character.

However, there is another characteristic of these two engines that identifies their date even more precisely - the light blue paint on the base. These are known as 'robin's egg blue' engines, which identifies their age precisely as that color was used for only two years: 1936 and 1937. Story there is that Tom Sr. picked up a deal on light blue paint in the middle of the Depression. Mrs. Jensen hand painted these on the kitchen table, but they did manage to keep the company in business. Quite a feat considering the economic conditions prevalent at that time.

Not a restoration, this engine is all original. Whenever possible, I like to get the story behind a particular engine - gives it a bit more personality. Here's the story behind this beauty.

This one came from Bob in Pittsburg. His uncle bought it in 1937 or 1938, which follows the Jensen timeline nicely - the robin's egg blue paint was only used in 1936 and 1937. When WWII came calling, his uncle packed it away (in the original box shown below) and headed off to war. There it resided until the late 1980's when it passed to Bob.

Note the chrome on the steam feed line. That's not polished, that's how it was when it came to me. Never tarnished. In excellent running condition. One test I like to make with Jensen engines is to close the feed line valve and spin the flywheel - it shows how tightly sealed the cylinder is. This one makes maybe 1/4 turn before it snaps back - the tightest compression I've ever seen on a Jensen engine.

Look carefully, this is what Jensen engines looked like when they left the factory in the late 1930's.
I've had this one for some time. In good running condition, though not quite as pristine as the one shown above.

Yet another example of the robin's egg blue riveted boiler 25. In quite good condition, other than some wear on the blue paint. In excellent running condition, all it needed was new sight glass seals and a new pressure relief valve. Jensen recommends replacement of the pressure valve on the older models. An excellent idea, I have noticed that the old pressure valves tend to leak steam easily.

Here is a slightly newer 25. Non functional when I found it, with a stripped out pressure valve hole, I have recently installed an intact boiler, and this old beauty has returned to running condition.
Note the plywood base, as opposed to the solid wood base of the three early 25's.

Riveted Boiler Jensen 5

I've been wanting a riveted boiler/robin's egg blue 5 for some time to round out my (affordable) riveted boiler Jensen group. This one pushed the envelope on cleanup jobs. About as rough as they come, 3rd and 4th photos are what it looked like when it arrived. Note the photo of the boiler - someone has mortared a heating element out of an iron to the bottom. A few taps with a brass mallet and most of the mortar fell apart. It shined up nicely, thanks to jeweler's rouge on a polishing wheel, and Jensen's habit of putting a very heavy nickel plate on the boiler. Need to find a heater, but otherwise this beauty is ready to go. Despite the rough exterior, the cylinder seems to have survived the abuse in remarkably good condition.
If this had been anything but a riveted boiler Jensen, I probably would have discarded it for parts, but I am rather partial to the riveted boiler.

Jensen 5

A real beauty. An earlier 5, in prime condition. Runs like a champion. If you run a 5 with no load, it cranks up some very high RPM's. Note the plywood base, as compared to the hardwood base on the early 25's. It appears that Jensen went to plywood bases after WW2, and discontinued wood bases altogether in, I think, the 60's. Feel free to correct me if I'm wrong on that...

Jensen 70

The other little wood base Jensen. Also an eager runner.

Jensen 35

Finally got a flywheel for this old fellow. Thanks, Roger!

Jensen 45

The bargain basement Jensen. Like most 45's this one has a steel boiler, and can't be fired out of fear of corrosion on the boiler.

Jensen 100

An older example of the workshop.

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