Rather than hijacking a thread on another obscure truck design, I'm starting a new one.

I was prompted to do some research on the early CP tender trucks when building a live steam Railroad Supply Corporation designed CP-173. I found the truck design on both the RRSC and the Disney (Lilly Belle) models of the CP-173 were functionally different than the prototype. The CP-173 is shown at http://ironhorsey.files.wordpress.com/2 ... cp_173.jpg

At Railfair 1991 at CSRM I found that the circa 1870 tender on circa 1920 Imperial Irrigation #151 had trucks that appeared to be identical to those used on CP-173, so took photos and measurements. I also took some photos of the CP Governor Stanford and found that those trucks were somewhat different than the ones on the CP-173 and #151.

The basic CP-173 and #151 truck design includes iron plate truck bolsters and side frames in one rigid unit. On the front truck the weight is carried by a cross equalizer and links. The rear truck is guided by a ball and socket and supported by side bearings on top of the springs which bear on the tender frame. The trucks on the Governor Stanford are somewhat similar and some of the casting numbers (journal box and cover?) are the same as #151, but the Stanford uses wooden truck bolsters. The Stanford doesn't use the ball and socket on the rear truck.

This style of truck seemed to have disappeared fairly quickly as locomotives were cycled through the shops and they were replaced with a more conventional/modern design. It's pretty remarkable that #151 managed to retain such an obsolete design.

The CP-173 was a major rebuild and redesign of an 1864 Norris locomotive that had been wrecked. I suspect that its and #151's trucks were a product of the Sacramento shops.

CP-173 front and rear trucks.

Imperial Irrigation District #151 front (two views) and rear trucks.

Governor Stanford front and rear trucks and one of the side bearings. (I don't have the photos marked as front and rear, but I'm surmising that the end of the rail is at the rear truck.)

IID #151 front king pin and spring cross equalizer. The cross equalizer is forged with a vertical hole through the middle and is a sliding/loose fit on the sleeve that circles the king pin. The end of the cross equalizer supports the weight on the springs through a band that circles the spring. I believe the top of the equalizer bears on a plate or socket surrounding the king pin. Bolster material is about 1" x 10".

IID #151 ball and socket on rear truck king pin. It appears that the only thing that kept the truck bolster from rolling forward or backwards on the ball was the weight on the wheels.

The vertical part of the casting behind the spring in the second photo apparently absorbs the side force against the spring. It must have been a trouble point as the casting has been broken and repaired with a bolted on strap. This photo also give an idea of how the end of the springs were supported on the side frames.

A couple of photos of the ancient tender behind IID #151. Axle spacing on each truck is about 45"

One of a journal on the front truck. My recollection is that the number cast into the journal and journal lid was the same on IID #151 and the Governor Stanford, which makes me suspect both were products of the Sacramento shops.

Finally, a couple more photos of the Governor Stanford.

I was apparently wrong when I said earlier that the front and rear trucks were the same. The pair of transverse springs is an interesting design. I believe these are both of the rear truck.

Maybe it's just my monitor, but on the Irritation Engine front truck the center of the cross equalizing beam looks like it has a convex spherical top that fits into a concave spherical plate under the car bolster with the king pin running up through the center of it - very loose hole of course to allow for tilt in all directions. Interesting to contrast with the joint shown on the rear, which is much more complex and prevents the truck from floating as far. Wonder why greater rigidity in the rear center plate was thought beneficial?

I can't tell what the cross equalizer rides on, but a spherical joint would seem to be good engineering practice.

I can't remember for sure how much play there was in the equalizer hole, but think it may have been loose. That may be due to design or it may have just been well worn after about 80 years in service.

This is fascinating! I had no idea this tender existed. How in the world did it become associated with a 1918 Alco 0-4-0T, and why is now being allowed to sit outdoors in Imperial?

If the 1870 date is correct then it may be one of the 7 or 8 oldest surviving tenders in the US, and probably the oldest slopeback tender.

Thank you for posting these pictures, Dick.

-Philip Marshall

I don't know how it got there. My guess is that IID wanted to supplement the water capacity of the tank engine that was used in an arid location and bought the tender as surplus from somewhere. Since the CP/SP discarded those trucks by the 1880s or so, I'm guessing the tender passed from the CP/SP's ownership long before IID got it.

As to date, I'm going by the truck design and appearance of the tender. It's not likely that those trucks would have replaced a more modern truck.

If that is a CP truck design, it's possible that CSRM would have some information on them.

I read somewhere that the group who returned it to operation in 1991 had just gotten old and tired and couldn't continue with the level of care that a steam locomotive needs.

(They apparently had a lot of fun with it - I seem to remember an oversized "Lipton" tea bag tag hanging from the steam dome for a while at Railfair.)

I'd be interested in anything anyone can turn up.

This type of truck was very common in the 1870-1890 period. The latest version that I have seen was on CStPM&O 4-6-0s built around 1900. These trucks were mostly used on 4-4-0s, and they show up in many photographs. I had seen them many times without thinking about how they worked. Then I became curious about that and did some research. I never did learn what they were named if they had a generic name. I asked John White, and he was familiar with them, but did not know what they were called. He thought they may have been called the “Ohio Truck.” I have never seen a photo showing this type of truck on any rolling stock other than locomotive tenders.

The main point of this truck is that all of the weight is carried on those side-bearing elliptical leaf springs. The photos poste here by Dick Morris are very helpful in shedding more light on these trucks. I do see what looks like a ball joint at the center bearing. That would be to allow the bolster to tilt in relation to the plane of the tender bottom frame. Not all of this type of truck had this ball joint.

The actual most unique feature of this type of truck is that all of the weight is carried directly down to the tops of the journal boxes. No weight is carried on the center bearing regardless of whether or not it has a ball joint. In order to carry no weight, the center bearing has a telescoping design.

In trucks without the ball joint, the center bearing simply telescopes and thus carries no weight. All it does is provide a fixed pivot point for the rotation or pivot of the truck. It uses an iron cylinder on the truck bolster, and another on the car bolster, with one cylinder fitting inside of the other in order to provide a telescoping connection. There is also a center pin involved. All of this is loose enough to allow some tilting of the truck bolster in relation to the tender.

I am not quite sure how the ball joint is arranged, but it appears that the ball joint is fixed to the truck bolster and the tender has a pin that telescopes through the ball. This would be a more precise type of bearing than just the loose clearance connection on this type of truck without the ball joint.

In any case, the ball joint is not just a simple ball joint with the ball fixed to the tender bolster and the ball cup fixed to the truck bolster. It also has a telescoping feature in order to avoid carrying any weight.

The trucks and iron tender frame on the tender attached to the IID shifter are absolutely AJ Stevens. Amazing to see them survive, and their construction intact.

AJ Stevens developed the truck and frame design by 1872. His successor HS Small developed his own version by 1895, gradually rebuilding engines to suit. By 1900 nearly all Stevens trucks were off the main line, although a tiny handful survived as late as 1908.

Stevens was a strong advocate of the iron tender frame. He installed iron tender frames on all CP tenders beginning in 1870 or 71, marking one of the first systemwide motive power standards under his watch. The value of the iron frame is demonstrated still today, for one of the four surviving Stevens iron tender frames still sees regular service underneath the tender attached to Baldwin-built V&T 25, where it was installed in 1935 by the SP Sparks shops after the original wooden frame failed in a derailment. (V&T management liked it so much that they wanted another frame for their No. 27. Sparks did not have one lying around the back forty, but Sacramento did, and suggested they come over and check it out.)

Unlike the frame, Stevens installed his truck and tender tank designs on as needed basis, whenever an wreck or rebuilding merited the ease of standard CP designed replacement. In fact, his rebuilding of the famous CP 173 was not so much a prototype for a series of production engines as often written, but as a test bed for repair and replacement parts - a set of cylinders, some wheels, a tender assembly, etc - that would be used whenever one of the 200 or so engines under his care required rebuilding or repair. Many of the scattered AJ Stevens parts that survive today are examples of this system.

The trucks behind the Gov. Stanford are not AJ Stevens. They were a standard Schenectady design, built around 1875-80, part of a Southern Pacific tender attached to the Gov. Stanford in the 1890s for display purposes.

So who was Stevens, and is this truck properly called the “Stevens Truck”?

I know that Dick Morris explained this in the captions, but I am confused about the detail shown in the ninth photo from the top. It shows an iron bar above the truck bolster, and parallel to it. I don’t understand calling this iron bar an equalizer.

What I refer to as the truck bolster is that fabrication of plates and castings that form a box-like cross section of a solid beam that is solidly connected to each of the truck side frames. So the bolster and the two truck side frames form a rigid “H” shape when looking down on it as in a plan view.

I don’t know if the cross structure is technically called a bolster since it is does not carry weight and does not sit atop springs. I believe that this arrangement of the solid bolster and truck side frames is fundamental to this type of truck. But I do not understand the purpose of the iron bar situated above the solid bolster, and was not aware of it other than seeing in these photos.

The iron bar widens out at its center in order to pass a round pin extending upward from the truck bolster. This iron bar also shows in the tenth and eleventh photo down from the top.

The ends of the iron bar appear to be connected to the top of the truck bolster where each end of the bolster connects to the truck side frames. In that sense, the iron bar would be one with the truck bolster. But I cannot see the point of it.

I assume that the tender weight is transferred to the trucks by the tender side sills resting atop the elliptical leaf springs as a typical feature of this type of truck.