Tender Booster

nw-mailing-list at nwhs.org nw-mailing-list at nwhs.org
Wed Oct 12 18:59:52 EDT 2005

A tender booster is a small piston engine operated by steam that is
clutched to the axles of the front tender truck. The booster is to
assist in starting a locomotive by supplying additional starting
tractive effort. As the locomotive accelerated to, I think, 10 mph or
so, the engineer had to disconnect the booster drive and turn off the
steam. Otherwise the unit would/could be damaged.

Some railroads applied boosters to many locomotives; some thought they
were mostly maintenance headaches and not worth the expense of
maintaining them.

As I recall, the Franklin booster was a two cylinder steam motor
connected by gearing and a clutch to the axle shaft. The clutch could
be disconnected, separating the booster from the axle so that the unit
would not be 'free-wheeling' or back driven by the tender wheels when
not in use. Leaving the clutch engaged would over-speed the cylinders
causing serious internal damage.

As a mechanical engineer, I can see that any mistake in shutting the
unit down and making the disconnect would result in big damage to the
unit- never small damage.

Good descriptions of the booster can be fond in steam-era Locomotive
Cyclopedia books.

G Rolih, Cincinnati

-----Original Message-----
From: nw-mailing-list-bounces at nwhs.org
[mailto:nw-mailing-list-bounces at nwhs.org] On Behalf Of
nw-mailing-list at nwhs.org
Sent: Tuesday, October 11, 2005 10:22 PM
To: nw-mailing-list at nwhs.org
Subject: Tender Booster

While looking through the collection of photos in the Virginia Tech
collection, I ran across two photos of a N&W Y-3 that had a significant
amount of piping between the locomotive and tender. One photo has the
notation "Application of Bethlehem Tender Booster 5-19-27." I have
never heard of a tender booster and wonder if someone can provide an

The photos are found at

and ....ns965.

Skip Chamberlayne

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