Steam & Excursion > Locomotive boosters, maintenance

Recently, with the return of 2102, discussion of locomotive boosters 
has cropped up.  I thought that I'd give some thoughts about the subject.

So I'll start with the 4 operating 'circuits' related to booster functioning.
The four system as are:
>The compressed air 'logic' control system.
>The steam "power" system
>The mechanical propulsion system 
>The human operator.

The operation  of the booster is sequenced by a system of timing reservoirs,
and two-position operating piston/cylinder 'operators.'
It firms an air-logic control scheme.

The steam power system obeys the paths and pistons as allowed by the 
air-logic.   Primarily, it's a two-piston engine, and a simple valve gear that
admits and exhausts the steam flow.  It is a one-direction engine...
it "powers"  only when going forward.

The mechanical propulsion system controls the power-link between the 
simple ( 2-piston) crankshaft and the geared, trailer-truck axle.
The key concept here is the two-position 'idler gear' that is positioned between
the crankshaft gear and the axle-gear.

The idler gear is mounted between two support arms, pivoted on the crankshaft.
When the engineer wants to start a train while using the booster, sets in place
the starting-timing system --- beginning with the warm-up cycle....

The warm-up cycle sends live steam to the pistons --- the idler gear is in
the 'dis-engaged' & NOT meshing with the axle-gear.  So, a warm-up 
cycle spins the crank shaft, blows water out of the 2-cylinder engine,
and warms-up the pistons, etc.

The warm-up cycle occurs with the idler gear in its raised position....
the Idler gear is constantly in-mesh with the crankshaft gear because the two
arms of the idler gear are pivoted from the crankshaft .... During warm-up,
the pistons, distribution valves, crankshaft and idker gear are all rotating
at a slow speed.

The key to the operation is whether the idler gear is engaged between the crankshaft 
gear AND the large diameter axle. 'bull-gear', on the rear-axle of the trailer truck.

The idler gear's center shaft is mounted on two bars, either side of the crankshaft,
'pinion gear' .... the arrangement of the two support bars, I call trunnions.

Steam for thr warm-up cycle comes from the appliance 'steam fountain', on the boiler
top, just in front of the cab. 

At the engineer's position is an air valve ( 2-position 'cock') for the warm-up cycle.

After a sufficient warm-up operation, the engineer prepares to depart, with the booster engine
engaged with the trailer truck axle....

The main difference between warm-up and 'powering' is the source of powering steam.
When powering, on departure, the air-logic operates a two-position flow-control steam valve
sending steam to the booster.  This steam supply comes from...


....paused...



Edited 5 time(s). Last edit at 04/27/22 17:47 by wcamp1472.

Are your referring to the type of booster for a steam locomotive in a trailing truck?

Booster engine for a Steam locomotive (cutaway drawing enclosed). This is a Franklin Railway Supply Co. model, one of the most common. From: https://en.wikipedia.org/wiki/Booster_engine

---

T&P came up with the idea of putting 2 booster engines on one of their 2-10-4's.  They said it worked well up to about 12 mph but even a Lima super power boiler could not continously feed 6 cylinders.  Steam pressure would rapidly fall.  It did not last long and the extra booster was removed.

What lubricant would they use in the gearbox? Are there modern lubricants that can be used?

ある時、punjtはgryipedwを見ました


wcamp1472 Wrote:
-------------------------------------------------------
> Recently, with the return of 2102, discussion of
> locomotive boosters 
> has cropped up.  I thought that I'd give some
> thoughts about the subject.
>
> So I'll start with the 4 operating 'circuits'
> related to booster functioning.
> The four system as are:
> >The compressed air 'logic' control system.
> >The steam "power" system
> >The mechanical propulsion system 
> >The human operator.
>
> The operation  of the booster is sequenced by a
> system of timing reservoirs,
> and two-position operating piston/cylinder
> 'operators.'
> It firms an air-logic control scheme.
>
> The steam power system obeys the paths and pistons
> as allowed by the 
> air-logic.   Primarily, it's a two-piston engine,
> and a simple valve gear that
> admits and exhausts the steam flow.  It is a
> one-direction engine...
> it "powers"  only when going forward.
>
> The mechanical propulsion system controls the
> power-link between the 
> simple ( 2-piston) crankshaft and the geared,
> trailer-truck axle.
> The key concept here is the two-position 'idler
> gear' that is positioned between
> the crankshaft gear and the axle-gear.
>
> The idler gear is mounted between two support
> arms, pivoted on the crankshaft.
> When the engineer wants to start a train while
> using the booster, sets in place
> the starting-timing system --- beginning with the
> warm-up cycle....
>
> The warm-up cycle sends live steam to the pistons
> --- the idler gear is in
> the 'dis-engaged' & NOT meshing with the
> axle-gear.  So, a warm-up 
> cycle spins the crank shaft, blows water out of
> the 2-cylinder engine,
> and warms-up the pistons, etc.
>
> The warm-up cycle occurs with the idler gear in
> its raised position....
> the Idler gear is constantly in-mesh with the
> crankshaft gear because the two
> arms of the idler gear are pivoted from the
> crankshaft .... During warm-up,
> the pistons, distribution valves, crankshaft and
> idker gear are all rotating
> at a slow speed.
>
> The key to the operation is whether the idler gear
> is engaged between the crankshaft 
> gear AND the large diameter axle. 'bull-gear', on
> the rear-axle of the trailer truck.
>
> The idler gear's center shaft is mounted on two
> bars, either side of the crankshaft,
> 'pinion gear' .... the arrangement of the two
> support bars, I call trunnions.
>
> Steam for thr warm-up cycle comes from the
> appliance 'steam fountain', on the boiler
> top, just in front of the cab. 
>
> At the engineer's position is an air valve (
> 2-position 'cock') for the warm-up cycle.
>
> After a sufficient warm-up operation, the engineer
> prepares to depart, with the booster engine
> engaged with the trailer truck axle....
>
> The main difference between warm-up and 'powering'
> is the source of powering steam.
> When powering, on departure, the air-logic
> operates a two-position flow-control steam valve
> sending steam to the booster.  This steam supply
> comes from...
>
>
> ....paused...

Great information! Boosters have always intrigued me, and they certainly did add punch to the power. Northern Pacific had 'em on several classes including the first Class A Northerns and Class Z-5 Yellowstones (!), but after WWII removed them as they were indeed very expensive and time-consuming to maintain. Thanks for this great post!



Edited 1 time(s). Last edit at 04/28/22 08:58 by kurtarmbruster.

After the warm up, the two way valve is moved to the run position and a "latch" is raised and latched on the power reverse quadrant, which tells the gear to engage with the axle gear.   After starting the train with the booster cut in, it stays engaged until the engineer hooks it up to a certain point which "knocks down" or disengages the latch and cuts out the booster.   You can also manually knock it down just by disengaging it with the reverse quadrant. There is also a valve in front of the engineer's lap with a push down lever on top.  If the booster starts to slip, push that lever down until it stops.  That stops the booster from slipping by cutting steam to it until you let off that valve.  Believe it or not, a booster can can slip.
Frisco was a big believer in the Franklin boosters as it helped them get out of town quicker.
I played around with 1522's booster several times and was convinced it is a good insurance policy.  It actually kind of bailed out on an NS trip out of St. Louis, over the Merchant's Bridge into IL.   Halfway up the bridge approach on a grade, we got a red signal and had to stop with the train hanging on the grade.  I was in the cab and warmed it up and engaged it.  When Jack Taylor got the signal, 1522 started that train and it was something to hear.  The little 4 cylinder exhaust mixing with the main exhaust, which at first was more of a whoosh until about 4-5 mph when the familiar shotgun bark commenced.  The booster was working until nearly the crest in the middle of the bridge.  I wish someone had videotaped that start!
I had occasion to play around with it a few times on the BNSF EAS in TX.  Did 3 runs from Haslet to a junction at Krum, turned there and went back to Metro Jct, turned again and tied up at Haslet between runs.   Turned and Krum and coming out on the main cut in the booster and also notched the diesel up to run 8 from 1522's cab and did an acceleration test.   Like a scalded cat!



Edited 1 time(s). Last edit at 04/29/22 14:58 by Frisco1522.

Fresco 1522..
Thank you for explaining the engagement of the booster...
Your 'real-life experience' is crucial to less experienced folks' appreciating
the engineer's operation of that powerful device.

I appreciate your explanation and your clarity, from the engineer's 
seat.

​W.

So, how do you service/oil the thing?  It appears to be encased in a big box - if I interpret all the bolt holes in the framework.  How are all those bearings lubed?

Lubricator for steam oil into the cylinders and today, PB&J in the "crankcase" which lubricates via splash lube.