SM-5030

SM-5030
l;
REVISION
ro· SERVICE MANUAL
5030
SERVICE MANUAL
5030
August, 1984
INSTALLATION AND
MAINTENANCE OF
In ol'.'der to maintain the
mechanical properties of the butting
fluid, it is recommended that a mixture
ot 10% Xerex and 30% deionized water be
used. Any ethylene glycol based coolant
per SAE specification J-814C may.be
used, provided it contains no sealant
type additives. Substituting tor the
deionized water may in combination With
the coolants, produce a precipitate
which Will inhibit the buffing action.
DOUBLE ACTING
OIL BUFFER
FOR SPRING SWITCHES
JULY, 1944
WESTINGHOUSE AIR BRAKE COMPANY
SIGNAL & COMMUNICATIONS DIVISION
Swissvale Post Office, Pittsburgh, Pa. 15218
An American-Standard Company
/
CONTENTS
PAR.
Double Acting Oil Buffer Applied to Spring Switch Layout
4
PART I.
GENERAL DESCRIPTION. . . . . . . . . . . . .
PART II.
(a)
(b)
(c)
(d)
(e)
(f)
INSTALLATION....................
Layout.. . . . . . . . . . . . . . . . . . . . . . . . . .
Connecting to Switch. . . . . . . . . . . . . .
Checking Oil Level................
Oil.. . .. .. . . .. .. .. .. .. .. .. .. . .. ..
Time Adjustment.. . . . . . . . . . . . . . . .
Winter Service....................
6
9
9
9
9
12
16
19
21
10
11
12
14
PART III. MAINTENANCE....................
(a) General..... . . . . . . . . . . . . . . . . . . . . .
(b) Piston Rod Packing..... . . . . . . . . . . .
(c) Lubrication.......................
(d) Method of Checking Performance...
24
25
28
29
PART IV. CAUSES FOR IMPROPER BUFFING ACTION
(a) Too slow or jammed...............
(b) Too fast.........................
(c) Unequal for Two Directions........
(d) "Kick Back"......................
General..... . . . . . . . . . . . . . . . . . . . . .
Draining Oil.. . .. .. . . . . . .. .. . .. . ..
Dismantling and Reassembling......
Valve operating shaft packing......
Stuffing Box Packing....... . . . . . . . .
3
15
15
15
16
17
32
18
18
18
18
33
19
34
20
20
20
30
31
v. OVERHAULING ................... .
PART
(a)
(b)
(c)
(d)
(e)
2
PAGE
36
39
41
49
21
21
22
Instructions for Installation and Maintenance
of Double Acting Oil Buffer for
Spring Switches
PART I
General Description
1. The double acting oil buffer is for use with spring
switches that can be trailed while set in either position.
When the switch points are trailed, the buffer offers no
resistance to the movement of the points away from the
stock rail but buffs their return until they reach approximately mid-position. Adjustable timing plugs are provided by means of which the desired buffing time can be
obtained for various conditions of installation and climate.
The buffer does not retard the movement of the switch
points when they are thrown by hand.
2. Fig. 2 shows the parts and will be referred to in the
description of operation. Fig. 2A shows the outline of
an older design of the buffer, before the oil chamber was
enlarged, but otherwise the description of Fig. 2 applies
to both designs. Except for the piston rod, the two ends
of the double acting oil buffer are the same. The space
between each piston and its respective cylinder head has
two connections to the oil chamber F, one of which is
through a small orifice in the timing plug (C at one end
and D at the opposite end) and the other is through a
check-valve (A and B respectively) which always allows
free entrance of oil as the piston is moved away from its
cylinder head. Push rod Sor E, acted upon by cam N-1
on shaft N, holds one or the other of the check valves
unseated, depending upon the position of the switch lever.
3. For a layout as illustrated in Fig. 1, a trailing movement will push the points toward the left, compressing the
spring in the head rod spring basket, and will cause the
buffer pistons to move toward the left (Fig. 2). Piston K
will not buff for either the outward or the return stroke
because valve Bis held unseated. Piston M moves toward
the left freely because its check valve A opens to admit
oil during the suction stroke. The displacement of the
switch points will suffice to shift piston M to the left of
leak groove H, so that when the wheels clear the switch
points the spring urged return of the points will force
the oil, which has been drawn in to the right of piston
M, back through the orifice in timing plug C. Check
valve A prevents this oil from returning through the large
port by which it entered. Piston M will uncover by-pass
leak groove H when the switch points have returned to
approximately mid-stroke, after which the points will
snap to the closed position. It should be noted that the
stroke caused by a trailing movement is necessarily more
than half the switch stroke as the switch point at the left
of Fig. 1 must be pushed over to accommodate the wheel
gage (i.e., 4 ft. 8~ in.).
4. When the hand throw lever is reversed, cam N-1
through push rod E will not allow check-valve B to seat
until the piston K has shifted far enough to be by-passed
by leak groove J, thus preventing the buffing action from
5
4
----~------------- · - - - -
-----------------------------
,,
0.
~
FIG. I
,ii@= t II lf:'11
H
MARKER AIBS CAST ON SIDE
POSITIONS VALVE OPERATING
·f·::.t~;"'.".'"~~~- ' , I
"I{
THE PROPER
~~i----------------------~--':~::~~~~7, .
-R
:cr~'~J1...11,~
.-~
STAINED
TO. THE PROPER LENGTH
ANGLE OF TRAVEL WILL BE
HAS BEEN AO.JUSTED
OF THE CYLINDER. THE OPERATING LEVER ANGLE OF
TRAVEL IS APPROXIMATELY 90il & IF VALVE OP[RATINC LEVER
ARM"R• SHOULD LINE UP WITH
IN 80TH NORMAL & REVERSE
·::.::,-:.:··.::·::::.·::::): ,::.· ::,i:--;;,_ ·::;: .i
SfCTION"'x-x"
SECTION"y-y"
~---·___,,,,..·
.J
,-----3'-3"'--+----l
being effective during hand throwing. After the reversal
of the hand throw lever, the functions of the two ends
of the buffer are reversed from that described.
5. An air chamber is provided at the top of the oil
reservoir to allow for the additional oil displacement of
the piston rod as the pistons are moved inward (i.e., from
left to right, Fig. 2), and to allow for temperature ex·
pansion of the oil.
PART II
Installation
Layout:
6. A general layout of tht; buffer applied to a switch
is shown in Fig. 1. This plan shows the spacing of the
ties and also notching and drilling dimensions required
for mounting the buffer.
7. Unless otherwise specified, the piston rod of the
buffer will be fitted with a screw jaw while the rod for
operating the valve will be fitted with jaw nut A (Fig. 1)
threaded for a 1% in. rod.
8. The valve shifting arm R and the stop arm G are
interchangeable on shaft N so that the buffer may be
applied to a layout as shown in Fig. 1 or to a layout having
the switch operating rod located back of the head rod,
and also to allow application of the buffer and switch
stand to be reversed from that illustrated in Fig. 1. Some
earlier designs of the buffer had no stop for the valve
operating shaft N. When the stop arm is not in place,
care must be exercised to prevent arm R being rotated
beyond the marker ribs, because the push rod guides may
be broken when the lug below the cam N-1 catches under
push rod S or E.
Connecting to Switch:
9. The buffer design provides 5~ in. maximum throw
of the piston rod. To adapt this buffer to a particular
switch stroke, proceed in the following manner:
10. Before connecting the buffer to the switch, push
the piston rod into the cylinder as far as possible (the
piston rod will strike the cylinder head), making a mark
on the piston rod at the end of the housing. Block the
8
9
switch in the middle position. Withdraw the buffer
piston rod 2% in. to its middle pos1t1on. Adjust the
screw jaw to the proper length for the hole in it to register
with the hole in the head rod and insert the pin.
11. Remove the block from the switch and measure
the total throw of the switch rod. The length of the valve
operating arm R should be adjusted so that the distance
between the center line of the shaft and the center of the
connecting pin will be 0.7 (seven-tenths) times the throw
of the' switch rod. Jaw nut A, Fig'. 1, should be assembled
securely on the end of the operating rod. The connecting
rod should then be attached to nut A and arm R and be
adjusted by means of the turnbuckle so that arm R is
opposite one marker rib when the switch stand lever is
normal and is opposite the other marker rib when the
switch stand lever is in the reverse position.
Checking Oil Level:
12. The buffer, Fig. 2, is filled with 9,Y2 pints of Pale
Semaphore Oil, Spec. 168, before it leaves the factory,
but the oil level should be inspected when the installation
is completed and ready for service. Check should be
made for leakage; all bolts, stuffing box nuts, plugs, etc.,
found leaking should be tightened. The buffer pistons
should be operated back and forth several times by operating the switch stand lever, leaving the switch with the
buffer piston rod in the "OUT" position. After carefully
cleaning (use a clean lintless cloth-not waste) around the
filler plug P to prevent entrance of foreign matter, remove
the plug and insert a clean wire to measure the distance
from the outside of the filler boss to the oil level. Do not
remove the filling screen unless it is clogged so that oil will
not enter.
10
13. For a buffer of the ·design shown in Fig. 2A, oil
should be added if the level is more than 1~ in. below
the top of the filler boss. To vent air which may have
entered the timing plugs if oil level was low, both timing
plugs C and D should be turned until prick punch marks
are opposite the figures "4" (See Par. 19) while filling.
14. For the buffer illustrated in Fig. 2, the buffer is
full when the oil level is not more than 2% in. below the
top of the filler boss, and will continue to operate satisfactorily with oil level 3 Ys in. below the top of the filler
boss. It is recommended, however, that in all cases of
inspection, the oil be left at 2 % in. or less. It will be
necessary to turn the timing plugs C and D so that prick
punch marks are opposite the figures "4" when filling this
buffer only if the oil level is found more than 3 Ys in. below
the top of the filler boss. The oil level may be allowed to
rise to the top of the filler hole; the oil level in reservoir F
can not rise above the bottom of the filler boss, in spite of
its height in the filling hole, because of the air pocket
surrounding the filling boss. Replace the filling plug,
being certain it is clean.
15. If oil is added, the switch should be operated
afterward several times with the filling plug in place and
then the oil level be again examined while the switch is
left so as to have the piston rod out. This is to insure
that any air which may have been trapped in the lower
parts of the buffer will have worked out. If the oil level is
found to have dropped, more oil should be added.
16. PALE SEMAPHORE 01L, SPEC. 168, which is especially
prepared in our factory by strainin.g through a silk
strainer, is shipped in sealed containers for use in the oil
buffer; no other oil should be used. A small clean funnel
11
with approximately ~ in. to % in. opening, fitted with a
fine mesh strainer, preferably fine silk, should be used.
17. CAUTION: The entrance of even small particles of
dirt or of lint, must be guarded against during filling.
18. Having made certain that the buffer is full of oil,
and after tightly replacing the filling plug, inspect carefully for signs of oil leakage and see that all bolts, stuffing
box nuts, plugs, etc., are sufficiently tight to assure a
bottle-tight container. The filler plug P must be bottletight; the appearance of bubbles or oil around the filler
plug as the switch is operated several times is evidence
that the plug is not tight.
0
(C)
Time Adjustment:
19. Three different buffing speeds are obtainable, depending upon which orifice in the timing plug registers
with the port into chamber F. There are four orifices
spaced 90 deg. around the sleeve of each timing plug C
and D, and numbered in the order of size, beginning with
the smallest, No. 1. No. 4 is so large as to give no buffing;
it is used for venting air when filling with oil (See Par.
12 and 13). A prick punch mark on the end of the timing
plugs C and D when aligned with figures 1, 2, 3, or 4
stamped on the stuffing box flange identifies the orifice
registration. When the buffer is shipped from our factory,
both timing plugs C and Dare set for No. 1 (the smallest
orifice, and the maximum buffing time). To change their
settings, loosen the timing plug stuffing box gland tap
screws sufficiently to allow the cover plate to be rotated,
exposing the slotted head of the timing plug. With a
screw driver, turn the timing plug to place the desired
orifice in use. Replace the cover and tighten the tap
screws.
20. Buffing time is tested before shipment by operating
the buffer piston with a 6 in. diameter by 5 in. stroke
pneumatic switch cylinder, the switch cylinder and buffer
being so connected that mid-strokes of both coincide.
Using 65 lbs. air pressure in the switch cylinder, the buffing
times are:
SHOP BUFFING TIME TEST
12
13
Fig. 3.
(a) Section thru timing plug C, Fig. 2.
(b) View showing numbers stenciled on top of stuffing
box flange, and prick punch on head of timing plug.
(c) Section of timing plug thru port orifices.
MIN,
MAX,
No. 1 hole. . . . . . . . . . . . . 30 sec. 40 sec.
No. 2 hole. . . . . . . . . . . . . 15 sec. 30 sec.
No. 3 hole. . . . . . . . . . . . . 10 sec. 15 sec.
No. 4 hole. . . . . . . . . . . . . No buffing
The actual time for return of the switch points after
they are cleared by car wheels will be less than that shown
.Y
PART III
by shop test, depending upon the trailed stroke, the
switch spring, friction, and the temperature.
Maintenance Instructions
Winter Service:
General:
21. In winter service in temperatures below freezing,
a small amount of moisture may accumulate in the oil
which may freeze in the small port openings of the valve
thereby preventing the buffer from operating. A smali
amount of alcohol, not exceeding one-half pint, may be
put in the cylinder. This will result in a non-freezina
mixture of alcohol and water, which will prevent thi;
trouble.
24. The buffer should be inspected occasionally.
Check the general operation, the alignment of valve operating arm R with the marker ribs on the castings, fastenings, signs of oil leakage, and the oil level, (Par. 12,
Page 10). The strainers on the bottom of timing plugs
C and D should be cleaned about twice a year. As the
normal oil level is above the top of the timing plugs, oil
will run out when these plugs are removed; fresh oil
must be added (Par. 16, Page 11) to restore the level after
replacing the plugs. If oil is changed in the fall and
spring (See Par. 23) the strainers may be cleaned while
the oil is drained. To remove the timing plugs C and
0, remove the tap bolts and gland, then insert a pointed
scriber or an 8-penny nail in the hole drilled through the
timing plug and lift it out. Use care to avoid damaging
either the small fibre gasket below the timing plug or the
gland packing. If the strainers are badly clogged this
indicates need for overhauling (See Part V, "Overhauling
of Buffer," Page 20), but otherwise carefully wash the
timing plug and its attached strainer in clean gasoline or
benzine and reassemble.
22. Buffers operating in sub-zero temperatures will
have~ tendency to slow up due to the slight stiffening of
the 011. In these cases the desirable speed may be obtained by adjusting the timing plug to the next larger
opening, as covered under "Time Adjustment" (Par. 19,
Page 12). If the No. 3 hole does not give the desired
speed, the oil may be thinned slightly by the addition of
a small quantity of Water White Kerosene, not exceeding
one and one-half pints.
23. To add alcohol or kerosene, it will be necessary
to draw off a small quantity of the oil by removina the
drain plug underneath the head of the cylinder orb; the
use of a hydrometer syringe or syphon.· When alcohol
or kerosene has been added in winter, the buffer should
be drained and be refilled with 9Y2 pints of Pale Semaphore
Oil, Spec. 168, in the spring.
14
Piston Rod Packing:
25. The piston rod packing should be kept sufficiently
tight to prevent escape of oil under pressure and yet not
be so tight as to interfere with free action of the buffer
when the switch is thrown by hand. The tightening of
the packing gland will be necessary only occasionally.
15
f
I
J,
Should the stuffing box nut at any time draw up solid on
account of worn packing, a new intermediate packing ring
Q may be added behind the outside end ring Y, taking
care that the V-shaped ring nests in proper direction
and that cut of new ring is staggered with respect to cut of
adjacent ring.
Checking Performance:
29. The operation of the buffer is best checked by
observing the motion of the switch points as a train
trails them. When there are no trains, the buffer operation
can be checked by reversing the switch stand lever while
the switch is blocked, and then knocking out the block,
allowing the spring to move the points.
26. Some of the earlier design buffers were equipped
with fibrous asbestos packing, shreds of which sometimes
entered the buffer cylinder and interfered with operation.
The complete replacement of the old style packing by
the new style is recommended when necessary to add
new packing but when the old style packing is to be
replaced, the buffer should be removed from service and
be sent to the repair shop to receive the attention stated
under the section "Overhauling of Buffer" (See Par.
49, Page 22).
27. CAUTION: Use great care to prevent entrance into
the buffer of any dust, dirt, or lint.
Lubrication:
28. The oil lubricates the interior of the buffer and the
piston rod packing. The outer end of the piston rod
where it passes through the guide and is exposed to atmosphere should be lubricated to prevent rusting and
binding on the guide. Fill the clearance space between
stuffing box nut and rod by applying light grease such as
Spec. 2513 through one of the lubrication fittings T
(Fig. 2) by means of a pressure gun. Operate the switch
by hand several times to see that rod when pulled out is
well coated.
16
17
Should the stuffing box nut at any time draw up solid on
account of worn packing, a new intermediate packing ring
Q may be added behind the outside end ring Y, taking
care that the V-shaped ring nests in proper direction
and that cut of new ring is staggered with respect to cut of
adjacent ring.
26. Some of the earlier design buffers were equipped
with fibrous asbestos packing, shreds of which sometimes
entered the buffer cylinder and interfered with operation.
The complete replacement of the old style packing by
the new style is recommended when necessary to add
new packing but when the old style packing is to be
replaced, the buffer should be removed from service and
be sent to the repair shop to receive the attention stated
under the section "Overhauling of Buffer" (See Par.
49, Page 22).
Checking Performance:
29. The operation of the buffer is best checked by
observing the motion of the switch points as a train
trails them. When there are no trains, the buffer operation
can be checked by reversing the switch stand lever while
the switch is blocked, and then knocking out the block,
allowing the spring to move the points.
27. CAUTION: Use great care to prevent entrance into
the buffer of any dust, dirt, or lint.
Lubrication:
28. The oil lubricates the interior of the buffer and the
piston rod packing. The outer end of the piston rod
where it passes through the guide and is exposed to atmosphere should be lubricated to prevent rusting and
binding on the guide. Fill the clearance space between
stuffing box nut and rod by applying light grease such as
Spec. 2513 through one of the lubrication fittings T
(Fig. 2) by means of a pressure gun. Operate the switch
by hand several times to see that rod when pulled out is
well coated.
16
'L
-,i
;
17
}
i
PART IV
Causes for Improper Buffing Action
30. Too Stow OR JAMMED:
(a) Timing plug orifices or strainers clogged.
(b) Foreign matter fouling the pistons.
Items (a) and (b) are indications that the interior of
buffer requires cleaning. The buffer should be removed
from service-see Part V, "Overhauling of Buffer,"
(Page 20).
(c) In extremely low temperatures, oil too thick
or containing moisture which, as ice, is
clogging ports.
(d) Piston rod packing taken up too tight.
31. Too FAsT:
33. Too MucH "K1cK-BACK":
"Kick-back" is a momentary rapid return movement
of the switch points before buffing becomes effective,
occurring as the points are released by the wheel flanges.
"Kick-back" is objectionable both because of the shock
as the buffing suddenly becomes effective on moving
parts, and because it allows the switch points to return
between successive wheels farther than the proper buffing
time would allow.
(a) Excessive wear of connection between head
rod and buffer piston rod.
(b) Oil level too low.
(c) Check-valves not seating properly; valve
fouled by foreign matter, broken valve spring.
(d) Wear of top and bottom holes in buffer
support.
(a) Oil level too low. (See Par. 12, Page 10).
(b) Check valves not seating.
The check valves may be examined by draining the
oil to below level of plugs and removing the valve plugs,
(See Par. 43, Page 21). The check valve may be improperly
held open by push rod-arm R not coinciding with
marker rib on casting due to improper length of arm R
or of connecting rod.
32. UNEQUAL FOR THE Two DIRECTIONS:
(a) Piston stroke not centered in buffer.
(b) Valve operating arm stroke not centered.
(c) One check-valve out of order.
(d) One timing plug orifice stopped up or set
different from the other.
18
19
PART V
Overhauling of Buffer
General:
34. Except for examination of check Yah-es, the clean·
ing of timing plug screens, and the checking of oil level
covered in Parts III and IV, the oil buffer should not be
taken apart in the field but should be removed to the
shop for repairs.
35. Caution must be exercised to keep all parts clean
when dismantled and reassembled. Do not use shop
air lines for blowing out buffer parts, because of possible
dirt particles carried in the compressed air. Use only clean
lintless cloths; do not use waste, because of its lint and
shreds. Repairs to the buffer should be made in a clean
atmosphere (i.e., not dusty).
D, and check valves A and B may locate the cause of the
trouble so that it can be corrected.
38. Whether the oil drained was clean or polluted, the
timing plugs C and D with their attached strainers, and
the filling hole strainer, should be removed and carefully
cleaned in gasoline or benzine (See Par. 24, Page 15).
Dismantling and Reassembling:
39. Remove the cylinder heads, withdrawing the
piston assembly with the stuffing box head. Do not with·
draw the piston rod from the stuffing box unless the packing is to be renewed, because this would injure the packing.
Renewal of cylinder head gaskets is advisable.
40. Remove push rods S and E to protect them from
damage; be careful to reassemble without interchanging
positions.
36. With the buffer mounted on a suitable support,
drain the oil through a clean fine mesh strainer (silk
preferred). Drain through one of the drain plugs U or
V, removing filler plug P to admit air. Place valve oper·
ating arm R over the marker rib away from the end
being drained, to hold the check-valve unseated. After
oil has drained from one end, it will be necessary to
remove the other drain plug to drain the other end,
shifting the valve operating arm R. Discard the drained
oil.
37. If the funnel strainer collects oil pollution, the
buffer must be dismantled for a thorough cleaning;
(See Par. 39, Page 21), but if the strainer shows the oil
to have been clean, inspection of the timing plugs C and
and B) with their attached springs; be careful to reassemble without interchanging positions. Clean the
cylinder, reservoir and valves with gasoline or benzine.
Examine valves and seats for damage; regrind the valve
seats if necessary, being careful to remove all grinding
compound.
20
21
41. Do not disturb the valve operating shaft N or the
shaft packings unless such packings are reported defective.
Defective packing for valve operating shaft N should be
replaced. Use one ring of -b in. Round Bar Durametallic
Grade D Packing first, followed by two rings of .Ys in.
Anchorite Asbestos Packing, Style No. 210.
42. Examine cylinder walls for scoring.
43. Remove the valve plugs and the check-valves (A
J
44. Wash the cylinder heads in gasoline or benzine.
45. If fibrous shreds are found inside the buffer, the
piston rod packing may be the asbestos type supplied with
some earlier designs of buffer. It should be replaced;
see Par. 49.
46. Wash the pistons in gasoline or benzine, being
sure that the rings are free in the piston grooves. It should
not be necessary to remove rings from pistons, but if so,
care should be taken to reassemble each one in its respective groove. Examine piston rod-see Par. 50.
47. Reassemble the buffer, omitting the filler plug, and
set the timing plugs C and D for the largest orifice (No.
4) to facilitate refilling. When filling, follow instructions
"Checking Oil Level," Par. 12 to 18 inclusive. The valve
operating arm R should be reversed several times during
filling, from its position over one marker rib to its position
over the other to insure filling at each end. The buffer
is not full until, with the piston out, reversal of the valve
operating arm R does not affect the oil level. After the
buffer is filled, set timing plugs C and D for No. 1 orifice.
to be removed is of the fibrous asbestos type, it is especially
desirable to clean the entire buffer because fibrous shreds
may have worked in from the packing; give the buffer the
attention stated in paragraphs 39 to 47 inclusive.
50. The piston rod must be uniform in diameter, not
worn, and free from nicks to give satisfactory results with
any packing. It should be in place before putting in the
new packing.
51. The rings of packing are furnished in wrapped sets
consisting of one inner end ring X, eight intermediate rings
Q and one outer end ring Y. Before installing the packing
make sure that flat steel washer W is in place first, then
install inner end ring X (tagged "bottom") with flat side
against steel washer, then nest the intermediate rings with
legs of V-shape towards buffer and with cuts staggered.
Assemble outer ring last. It may be that one intermediate
ring may have to be omitted to permit assembly of stuffing
box gland and nut. Draw up nut only enough to hold oil,
without seizing the rod.
Timing Tests:
48. It may be desirable to check buffing time in the
shop as outlined in Par. 20, Page 13.
Replacement of Stuffing Box Packing:
49. When replacing stuffing box packing (as called
for in Par. 26, Page 16 and by Par. 45, Page 22) the old
packing should be removed carefully making sure that
the stuffing box is free of all loose particles. If the packing
22
23
I
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