Steam & Excursion > Booster engine - how are they controlled?

I know that some steamers had a booster engine for additional tractive effort when starting, with the booster engine either attached to the trailing truck or beneath the tender. How were they controlled? It would seem that a separate throttle of some sort would be needed, given the requirement to cut it out at speed. Was it a small quadrant type throttle or just a small valve. Were they two speed beasts (off / on) or could they be throttled in some manner?

I have information on a Franklin air controled system. There were likely others, but this is what I have.

"Operation of the booster is automatic. When the engineer needs the extra power of the booster, he raises the control latch on the quadrant. The booster goes into gear and simultaneously steam is admitted to the booster engine.
"When the engine is hooked up a predetermined distance, the latch drops down, the steam is cut off from the booster which then goes out of gear. No additional duties are imposed upon the engine crew. The entire control is so designed as to preclude the possibility of accidental engagement of the booster."

The control latch turned on the Pilot Valve, an attachment to the locomotives quadrant which sent an pneumatic signal to a clutch valve and cylinder to engage or disengage the booster engines idler from the drive gear. It was engaged only when in full forward.

Pneumatic lines connected a transponder on the dry pipe to the boosters remotely controlled throttle valve to tell it to open when there was pressure in the dry pipe. The booster steam supply came from the dry pipe (or the delivery pipes beyond the superheater), but the aforementioned transponder assured that the locomotives throttle was open.

Reversing or setting cutoff was not possible.

Cylinder cocks were controlled by a separate pneumatic line controlled by a three-way cock in the cab.

On 4 wheel locomotive and tender trucks, the engine only powered one axle, with side rods on tender trucks to provide power to both axles, but I don't believe siderods were ever applied to loco trucks. A six wheel tender truck was also offered, but offhand I can't think of any applications. This also powered only one axle, but siderods linked to the second, but not the third axle.

That's good info. Now...as for the siderods that allowed for both axles of a tender trailing truck to be powered by the booster, off the top of my head, the only such engines so-equipped I can think of were the Boston and Main engines. SO...weren't most engines equipped with a booster (such as SP4449, TP610)...would these examples have just one booster driven axle in the trailing engine truck? Second question: was it the lead, or trailing axle?

I once had the record that had extensive recordings of the American Freedom Train. One segment, on starting, said "If you listen to the 4449 on startup, you will note the shaylike sound which indicates that Doyle McCormack has engaged the engine booster". I listened to that track over and over and over again, and never heard a "Shay-like sound", or anything out of the ordinary that told me I was hearing a booster. So, does anybody have a good description of what the sound was like? Was it just a rapid-fire, pumping type of a noise?

Red Wrote:
-------------------------------------------------------
> would these examples
> have just one booster driven axle in the trailing
> engine truck?

Yes.

> Second question: was it the lead,
> or trailing axle?

Trailing axle on engine, leading axle on tenders.

> does
> anybody have a good description of what the sound
> was like? Was it just a rapid-fire, pumping type
> of a noise?

I can't help you there.

---

I have seen a video of 2716 hard at work at low speed with the booster on, and the sound is simply that of rapid steam exhaust, much like a Shay would put out. Sounds really neat mixed in with the regular cylinder exhaust.

Weren't the IHB 0-8-0s equipped with side rodded tender trucks?

MArty Harrison

Frisco 1522 has a Franklin booster on the trailing truck and it's a nice little insurance policy which came in handy a few times. It also helps get you up and moving so that you can work up to track speed quicker.
There's a two position air valve below the reverse quadrant which in one position allows you to idle the booster. Prior to using, we would start the hydrostatic lubricator, the idle it for a few minutes to warm it up and spread lubrication. The booster cylinder cocks stay open for a period of time, then close. Then the air valve is changed to the run position. The lever which engages (knockdown lever) the booster is pivoted up and locked when the reverse lever is in the corner and this engages the booster. When the engine throttle is opened, the booster also receives steam and starts to work. The C2 is usually good to about 15-18 mph, and can be engaged while the engine is moving. It works in forward only.
After the engine is moving and you start to hook her up, you'll reach a point on the quadrant where the knockdown lever will drop out and disengage the booster. You can also manually do the same by "knocking down" the lever. There's also a button air valve that you can depress do momentarily disengage the booster if it slips. (Yes, they do slip sometimes)
If you can picture a two cylinder steam locomotive with 44" drivers and softer exhaust doubleheading with an engine with 69" drivers, this gives you an idea what sounds it makes. The booster exhaust on the 1522 exits through a separator/muffler in front of the cab and I suppose it does sound kind of like a shay.
When we were originally restoring 1522, we had the booster engine removed and sitting on cribbing until we reconditioned it, then entertained everyone by running it on air.
Those who know me still call me by a nickname I acquired early in my career as a 1522 engineer.

Thanks gang