Steam & Excursion > To Swab or Not to Swab...

Titled, With apologies to The Bard, who died five hundred years ago and probably doesn't care much today anyway.

A swab is a c-shaped metal clip wrapped in Wool yarn used to lubricate the piston rod on an air compressor. There seem to be several theories about their use. Are they really needed?

1. Use them, remove them daily and soak them overnight in hot valve oil to reinstall in morning.

2. Leave them installed overnight pouring hot valve oil on them in the morning.

3. Leave them installed, never lubricate them.

4. Tell me again, what's a swab?

-LD

What does your favorite tourist railroad do?



Edited 1 time(s). Last edit at 08/21/17 14:37 by LarryDoyle.

Probably it's determined by the type of rod 'packing' used.

Conventional rope packing, versus 2-piece 'Metallic packing'

Probably swab for conventional packing... probably aids the packing in the air cylinders.
The same, hot, rod enters the air cylinders, so the air cylinder packing could benefit the most from the additional lubrication.
I would use superheat valve oil for that purpose.

I have seen swabs that reminded me of C-shaped clamps used by bike riders , and their pants legs, near the ankles.
The steel clamp was wound with cord(?) and thoroughly soaked in oil... The open end allowed you to easily snap the swabs off and on the rods.

Newly applied Metallic packing* may blow for a short period tim, during break-in

So , I would swab during the break-in . Once, metallic packing got 'seated', probably unnecessary.

FWIW.

W.

* U.S. Metallic Packing Co., Staten Island, NYC. Sold 2-pc. Packing ( " King Metallic Packing", also air compressor pump-operated, 2 compartment, air compressor lubricators) specifically for C.C. air compressors.

The 2-pc. Packing was machined from their packing-metal formulation, machined and ready to go....the machined toroidal packing was sawn with a precision tool, and the cuts were spiral segments....

The spiral cuts allowed the two pieces to grip the rod, tighter and tighter, as the packing wore,
The top of the packing 2-pc. ring was cut at a 45-degree angle, which fit into a matching, steel female 45-deg. 'cup', compressed by the large packing nut around the rod. Below the 2-pc. packing was a stout spring, which forced the 2-pieces in to the matching cup, & thus, tighter and tighter onto the rod.



Edited 6 time(s). Last edit at 08/21/17 15:19 by wcamp1472.

We leave the ones on # 40's air pumps on all the time and occasionally give them a hit with steam oil. They tend to keep the exposed portion of the rod well covered with a thin film of oil.

Ross Rowland

All the reason why a good chrome job on the rods is important, the porosity in the chrome surface
holds the lube film without affecting the seal. Rope is easy because the nut can be tightened if
it leaks and it can be changed easily when needed. Energized cups or metal backed cups can only be
changed when the compressor is fully or partially torn down.

Out

wcamp1472 Wrote:
-------------------------------------------------------
>
> Probably swab for conventional packing... probably
> aids the packing in the air cylinders.
> The same, hot, rod enters the air cylinders, so
> the air cylinder packing could benefit the most
> from the additional lubrication.

Yes, as the steam side is lubricated by either a hydrostatic* lubricator in the cab, or a mechanical lubricator on the pump. (* Newbies note: "hydrostatic lubricator" is another way of spelling "pain in the A$$". I fought with one yesterday.)

-John

I'll have to talk LarryDoyle, in between his movie roles, to 'splain' those dangerous beasts, under a different subject heading.

Hart's ex-CP, 4-6-0, # 972 ( ca. 1910) was equipped with one. We thought we had the pressure bled-off.
Guess What!

POWWW... we didn't have it bled...
Boiler pressure blew the loosened fill plug into the cab roof, and valve oil splattered all over the place...
The steam had been shut off , but there was pressure trapped in housing...

I never did master those things....again, I was a very inexperienced newbie.....an example of why Ben Kantner, Hart's Loco Chief, hated "newbies" in the cab of fired-up, excursion locos.

He was deathly afraid of youngsters getting hurt ( several were killed at the RDG's, St. Clair, PA. roundhouse ---- during WW2---- where Kantner was supervising). So, yes, these things can be very DANGEROUS...

W.



Edited 4 time(s). Last edit at 08/21/17 17:26 by wcamp1472.