A lubricant pump that includes a pneumatic piston motor operated by compressed air, and is equipped with a control device that utilizes a slide valve mounted for reciprocal axial movement on the piston rod. A radially acting spring locking mechanism includes two index grooves spaced from each other axially along the piston rod, separated by the same predetermined distance that separates a first air inlet position and a second air inlet position of the piston slide valve. A helical compression spring is contained in a cavity within the piston slide valve. Axial movement of the reciprocating piston rod in one direction compresses the spring and releases the locking mechanism, whereupon the compressed spring immediately expands and moves the slide valve from one of its air inlet positions to the other of those positions. Four annular, substantially airtight, slidable contacts are provided to isolate the helical compression spring and the releasable locking mechanism from compressed air flowing into, and air at lower pressure flowing out of, the control device.

FIELD OF THE INVENTION 
This invention relates to a lubricant pump that delivers lubricant from a 
lubricant source to an outlet bore, and more particularly such a pump in 
which the reciprocating movement of the piston rod of the pump is produced 
through the use of compressed air. 
BACKGROUND OF THE INVENTION 
In one air-operated lubricant pump known in the prior art, disclosed in 
European patent No. EP-OS 0 039 418, a rotary slide valve that alternates 
the side of the piston on which compressed air is introduced is connected 
to the reciprocating piston rod of the pump by means of a slideway, and 
every time the piston rod moves to one of its end positions the rotary 
slide valve changes its angular position through the pressure of a hairpin 
spring. Between the end positions of the piston rod, the rotary slide 
valve is kept in its desired angular position by means of a control bar. 
Compressed air is introduced into a tubular chamber in which the slide 
valve moves, and is routed through ports in a front wall of the tubular 
chamber. 
One of the shortcomings of this prior art device is that a hairpin spring, 
which relies on a single bend, is more susceptible to failure than a 
spring of the type employed in the present invention, i.e., a helical 
compression spring. A second shortcoming is that in this prior art device 
compressed air flows constantly around the hairpin spring, and this 
continued exposure to compressed air decreases the useful life of the 
spring. Another shortcoming is that the installation of this prior art 
control device is quite difficult. 
Another type of air-operated lubricant pump, disclosed in German patent No. 
35 27 925, is one in which an axially movable slide valve is utilized to 
change the side of the piston on which compressed air is introduced, as 
the piston moves forward and backward to produce a pumping action. This 
prior art device is not automatically operated, but relies on manual 
operation of a two-position valve for introduction of compressed air into 
the device. The cylindrical slide valve has a complicated arrangement of 
air passages extending through its walls. Because of the construction of 
this prior art device, the reversal of direction of the reciprocating 
piston rod is effected by pressure differences within the slide valve, 
which makes a waiting period necessary for the individual air passages and 
chambers to be aerated and de-aerated before the piston rod reverses its 
direction. 
The air-operated lubricant pump of the present invention avoids the 
indicated shortcomings of the prior art, and provides reliable, economical 
and automatic reciprocating movement of the piston rod with a minimum of 
maintenance for long periods of time. The manufacture of the device is 
much simpler than the manufacture of the second prior art device just 
discussed, because there is no necessity to cast or bore any maze-like 
passages through the walls of the cylindrical slide valve, as is the case 
with the prior art device in question. 
SUMMARY OF THE INVENTION 
The mechanism of this invention includes a slide valve mounted for axial 
movement, (1) back and forth on the piston rod of a lubricant pump, and 
(2) within a slide valve-receiving chamber in a control casing that is 
attached to the pneumatic cylinder of a reciprocating piston. The piston 
slide valve has the general form of a hollow cylinder with an imperforate 
wall. The external surface of the cylindrical wall of the slide, valve 
defines, a plurality of annular air channeling grooves in axially spaced 
positions that provide interconnection of the air inlet port with either a 
forward stroke conduit or a return stroke conduit, which conduits lead to 
opposite sides of the compressed air piston of the pump. There are 
preferably three such grooves, each of which extends continuously, without 
interruption, around the slide valve, and lies in a single plane 
positioned at right angles to the longitudinal axis of the valve. 
Which of the conduits is thus connected with the air inlet port depends 
upon whether the slide valve is in a first air inlet position or in a 
second air inlet position. These positions are separated by a first 
predetermined distance measured, along the piston rod. 
The slide valve has an inwardly directed flange a portion at each end that 
is positioned in close radial proximity to the reciprocating piston rod, 
and a central portion lying between these end portions that is spaced from 
the piston rod to form an elongated cavity of annular cross section 
between the piston rod and the cylindrical inner wall of the slide valve. 
Sets of annular intermediate air passages are formed within the control 
casing (preferably immediately adjacent the piston slide valve) which 
cooperate with selected pluralities of the air channeling grooves on the 
external surface of the piston slide valve. When the slide valve is in its 
first air inlet position, one set of annular, substantially airtight, 
intermediate air passages is formed which helps define a first air entry 
path and an associated first air exit path. When the slide valve is in its 
second air inlet position, another set of annular, substantially airtight, 
intermediate air passages is formed which helps define a second air entry 
path and an associated second air exit path. 
The element that forms these airtight, intermediate air passages has an 
inwardly facing surface that makes an annular, substantially airtight, 
slidable contact with the outer surface of each end portion of the piston 
slide valve. In addition, it has an outwardly facing surface that makes an 
annular, substantially airtight contact with the inner wall of the control 
casing adjacent each of the opposite ends of the slide valve. This 
arrangement of parts provides a slide valve-receiving channel within the 
control casing. The four contacts are at all times located farther axially 
from the central portion of the slide valve-receiving channel than are (1) 
the channeling grooves on the slide valve, (2) all the intermediate air 
passages, and (3) all openings in the inner wall of the control casing 
that lead away from the passage-forming element. 
The four annular, substantially airtight contacts just described 
substantially isolate the interior space within the slide valve from (1) 
compressed air that enters the air inlet port and passes through one of 
the first and second air entry paths described above, and (2) outflowing 
air at lower pressure that passes through the air exit path associated 
with that one air entry path, and from there out through the air discharge 
port. By the same token, these four annular, substantially airtight 
contacts preferably isolate the slide valve releasable holding means 
described just below from the compressed air that flows into, and from the 
air under lower pressure that flows out of, the mechanism of this 
invention. 
The mechanism of this invention includes means for releasably holding the 
piston slide valve in one or the other of its first and second air inlet 
positions, which positions are separated by the above mentioned first 
predetermined distance measured between their center lines and along the 
piston rod. The length of the slide valve-receiving chamber in the control 
casing that is referred to above is at least substantially equal to the 
external length of the slide valve plus this predetermined distance 
between the first and second air inlet positions of the slide valve. The 
holding means is adapted to be released by the application to the slide 
valve of an axially directed force of at least a predetermined minimum 
magnitude. 
A helical compression spring is positioned within the elongated annular 
cavity in the piston slide valve. This spring is adapted, when in a 
compressed condition, to apply an axially directed force to one of the end 
portions of the slide valve. 
First actuator means is positioned on the reciprocating piston rod for 
pushing the helical compression spring against one of the end portions of 
the slide valve, when the piston rod moves in a given direction, to place 
the spring in a compressed condition. Second actuator means is positioned 
on the reciprocating piston rod for pushing the compression spring against 
the other slide valve end portion, when the piston rod moves in the 
opposite direction. 
Means is provided for releasing the holding means by applying to the piston 
slide valve an axially directed force of at least the above mentioned 
predetermined minimum magnitude, first in one direction and then in the 
opposite direction, as the reciprocating piston rod moves alternately 
through its forward stroke and then through its return stroke. 
When compressed air is introduced from the air inlet port, through either 
the forward stroke conduit or return stroke conduit, into the pneumatic 
cylinder on the side of the compressed air piston that is associated with 
the conduit in question, the compressed air piston and piston rod will be 
pushed toward the opposite side of the compressed air piston. Either the 
first or second actuator means is thereby moved axially to compress the 
helical compression spring so that when the holding means is released, the 
compressed spring immediately expands and moves the slide valve from one 
of its air inlet positions to the other of those positions. 
In one embodiment of the mechanism of this invention, the holding means is 
released by a force applied by the helical spring itself, in a condition 
in which it is either fully compressed or nearly so. In the preferred 
embodiment, a third actuator means is fixedly positioned, between the 
first and second actuator means, on the portion of the reciprocating 
piston rod that is located within the annular cavity of the slide valve. 
This third actuator means applies to one of the end portions of the slide 
valve an axially directed force of at least the predetermined minimum 
magnitude that is required for release of the holding means. 
Other features and specific forms of the mechanism of this invention are 
disclosed below.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
Preferred Embodiment 
The sectional view of FIG. 1 illustrates a preferred embodiment of a 
compressed air-operated mechanism for the reciprocating piston rod of a 
lubricant pump in accordance with this invention. In this view the 
reciprocating piston rod of the pump is carrying out its return stroke. 
General Construction 
The air-operated mechanism illustrated in FIG. 1 includes pneumatic 
cylinder 1, which comprises side wall 3 and end wall 3a. Compressed air 
piston 2 performs reciprocating axial movement within cylinder 1 as 
compressed air is introduced first on left-hand side 2a, and then on 
right-hand side 2b, of the piston. Compressed air piston 2 has an 
airtight, slidable contact with the internal surface of side wall 3 of 
cylinder 1. Reciprocating piston rod 7 carries at its opposite end 10 a 
working extension piece (not shown), which is the piston of the lubricant 
pump. 
In the embodiment shown, compressed air piston 2 has a large diameter, and 
the piston of the lubricant pump with which this mechanism is used has a 
smaller diameter, to produce high pressure. The relative size of the 
pistons at each end of piston rod 7 may of course be varied, in a manner 
well known, depending upon the level of pressure desired in the pump. 
The mechanism of FIG. 1 is completed by control casing 6, attached to 
pneumatic cylinder 1, and the control device contained in that casing. As 
best seen in FIG. 1, wall 6a of control casing 6 forms one end of 
pneumatic cylinder 1. The control casing terminates at its opposite end in 
flanged neck 11. 
Piston rod 7 is slidably journaled in the walls of control casing 6 (both 
in the main body of the control casing and in flanged neck 11) for 
reciprocating axial movement between a forward position and a return 
position. Piston rod 7 is guided by bushings 8 and sealed by means of 
packing rings 9, located at each end of casing 6 (see FIGS. 1-3). 
The walls of control casing 6 contain compressed air inlet port 24 and air 
discharge port 25. Inlet port 24 is adapted to supply compressed air to 
the control device contained within control casing 6. Forward stroke 
conduit 4, formed in the walls of control casing 6 and in wall 3 of 
pneumatic cylinder 1, leads from the control device to the left-hand side 
2a of compressed air piston 2. Return stroke conduit 5, in the wall of 
control casing 6, leads to the other side 2b of piston 2. 
Piston Slide Valve 
Piston slide valve 14 lies at the center of the control device contained in 
casing 6. Slide valve 14 has the general form of a hollow cylinder with an 
imperforate wall. The external surface of the generally cylindrical wall 
of slide valve 14 defines a plurality of annular air channeling grooves 
26, 27 and 28 spaced axially from each other on that surface. As will be 
described in more detail below, grooves 26, 27 and 28 provide 
interconnection of air inlet port 24 with either forward stroke conduit 4 
or return stroke conduit 5, depending upon the position of the slide valve 
within control casing 6. 
Slide valve 14 has a first air inlet position (seen in FIG. 3) in which it 
connects air inlet port 24 to forward stroke conduit 4, and air discharge 
port 25 to return stroke conduit 5. The term "forward stroke" is used in 
connection with the Figures of the drawing to refer to movement of piston 
rod 7 towards the right side of the Figure, and the term "return stroke" 
is used to refer to movement of the piston rod to the left. The slide 
valve has a second air inlet position (seen in FIGS. 1 and 2) in which it 
connects air inlet port 24 to return stroke conduit 5, and air discharge 
port 25 to forward stroke conduit 4. The two air inlet positions of the 
slide valve are separated by a first predetermined distance. The slide 
valve is movable back and forth along piston rod 7 within slide 
valve-receiving chamber 13 in control casing 6, between the two air inlet 
positions of the slide valve just described. 
Each end of slide valve 14 has an inwardly directed flange portion that 
lies in close radial proximity to reciprocating piston rod 7 at end 
portions 14a and 14b, when the piston rod is in its midposition between 
its forward and return positions. The slide valve moves along the piston 
rod within chamber 13, which extends around and along piston rod 7 within 
control casing 6. 
The length of slide valve-receiving chamber 13 is at least substantially 
equal to the external length of slide valve 14 plus the first 
predetermined distance separating the first and second air inlet positions 
of the slide valve. This relationship can best be seen at the left end of 
the slide valve in FIGS. 1 and 2, and at the right end of the slide valve 
in FIG. 3. As will be seen the spaces that are provided between the right 
and left ends of the slide valve and the corresponding inner end walls of 
slide valve-receiving chamber 13 allow the slide valve to move axially, 
during the operation of the mechanism of this invention, from its first 
air inlet position (FIG. 3) toward the right to its second air inlet 
position (FIGS. 1 and 2), and back again at the left. In the embodiment of 
this invention shown in FIGS. 1-4, grooves 26, 27 and 28 extend 
continuously, without interruption, around the piston slide valve. Each of 
the grooves lies in a single plane positioned at right angles to the 
longitudinal axis of the slide valve. 
Releasable Holding Means 
Part 15 of end portion 14b of the slide valve --together with three 
locating elements 32 (of which two are indicated in FIG. 1) that are 
spaced circumferentially around part 15 in a plane normal to the 
longitudinal axis of the slide valve--comprise a spring-locking mechanism. 
This mechanism holds the slide valve releasably in either its first or its 
second air inlet position. 
The external surface of part 15 of the slide valve includes two index means 
16a and 16b, in the form of grooves extending circumferentially around the 
slide valve. The center lines of these grooves are spaced from each other 
along the external surface of the slide valve by the above mentioned first 
predetermined distance that separates the slide valve's first and second 
air inlet positions. When the spacing of any two indexing elements such as 
grooves 16a and 16b is referred to in this specification or in the claims, 
it is the spacing of the center lines of the two elements that is referred 
to. 
Each locating element 32 comprises a spring-biased spherical ball 
positioned within the walls of control casing 6. The spring loading of the 
spherical balls is provided by helical compression springs 17 (one of 
which is shown in the broken-away view in the lower right-hand portion of 
FIG. 1) that press the balls radially toward slide valve 14 to position 
the balls normally within either index groove 16a or 16b. 
When spring-loaded spherical locating balls 32 are seated in groove 16a (as 
in FIG. 3), slide valve 14 is in its first air inlet position. When 
locating elements 32 are seated in groove 16b (as in FIGS. 1 and 2), the 
slide valve is in its second air inlet position. 
When an axially directed force is applied to slide valve 14 to move it to 
the left in slide valve-receiving chamber 13 from the position shown in 
FIGS. 1 and 2 to the position shown in FIG. 3, the holding action of 
spring-locking mechanism 16b/32 can be overcome only if the axially 
directed force is sufficiently large. In other words, the axially directed 
force must be of at least a predetermined minimum magnitude. 
The minimum axially directed force required to release spring-loaded 
mechanism 16b/32 depends, as can be seen, upon the magnitude of the force 
applied radially against spherical locating balls 32 by compression 
springs 17. In the preferred embodiment illustrated, the radially directed 
pressure exerted by springs 17 on spherical balls 32 can be adjusted by 
rotation, in one angular direction or the other, of the associated 
adjusting members 17a, which are in threaded engagement with the walls of 
the respective access ducts 17b. Each access duct extends to the external 
surface of the circular flange of flanged neck member 11 that comprises 
the end wall of control casing 6. This makes each adjusting member 17a 
accessible to a tool inserted in the duct from outside the mechanism. 
Helical Compression Spring 
As already stated, end portions 14a and 14b of slide valve 14 are in close 
proximity to piston rod 7. The central portion of the slide valve lying 
between end portions 14a and 14b is spaced from the piston rod to form an 
elongated cavity 14c of annular cross section within the interior of the 
slide valve between the piston rod and the wall of the generally 
cylindrical slide valve. Helical compression spring 29 is located in this 
cavity. 
In the embodiment shown, piston rod 7 comprises two rod elements on the 
left-hand and right-hand sides of FIG. 1, with one intermediate piece 12 
between these two rod elements. Intermediate piece 12 of piston rod 7 has 
a reduced diameter compared to the rod elements on either side of the 
intermediate piece. As will be seen, this intermediate section 12 enlarges 
the inner radial dimension of elongated annular cavity 14c within slide 
valve 14, thus contributing to the space for compression spring 29. 
Each of the portions of reciprocating piston rod 7 that lies on either side 
of reduced portion 12 of the piston rod forms a shoulder 31 at the point 
where it joins the reduced portion. An annular shaped washer 30 is 
slidably carried by reduced portion 12 of the piston rod adjacent each 
shoulder 31. (Members 30a and 31a are on the left-hand side, and members 
30b and 31b are on the right-hand side, of FIGS. 1-3.) Each of these 
washers has an outside diameter that is larger than the inside diameter of 
end portions 14a and 14b of slide valve 14 that are closely adjacent 
reciprocating piston rod 7, thus ensuring contact between these end 
portions and the washers when they move axially toward each other. In 
order to ensure that contact will be made between a washer 30 and helical 
compression spring 29 when those members move axially toward each other, 
each washer 30 has an inside diameter that is smaller than the outside 
diameter of helical compression spring 29. (In FIGS. 1-3, as will be seen, 
the preferable inside diameter of each washer 30 is still smaller than 
just specified, being only slightly larger than the diameter of reduced 
portion 12 of piston rod 7 on which it slides.) 
As a result of the dimensions just indicated, an axially directed force, as 
for example a force directed to the left by shoulder 31b on the right-hand 
side of FIG. 1 as piston rod 7 moves to the left, will be transmitted to 
the associated washer 30b and from there to the helical compression 
spring. The helical compression spring will then apply this force to 
washer 30a at the left end of reduced intermediate portion 12 of the 
piston rod, and will push the latter washer against inwardly directed end 
portion 14a of slide valve 14 after the piston rod has moved a short 
distance to the left from the position it occupies in FIG. 1. 
The continued movement of piston rod 7 to the left will cause washer 30a to 
slide along reduced intermediate portion 12 of piston rod 7 (to the right 
relative to the rod), thereby further compress helical compressing spring 
29 between the two washers 30a and 30b at each end of the spring. As seen 
in FIG. 2, at this point washer 30a is exerting a force directed to the 
left against end portion 14a of slide valve 14, while the other end of the 
slide valve is held by the holding mechanism comprised of spring-loaded 
spherical balls 32 in engagement with index groove 16b. 
First, Second and Third Actuators 
From the foregoing discussion, it will be seen that shoulder 31b on the 
right hand in FIG. 2 acts as an actuator for pushing compression spring 29 
against end portion 14a of slide valve 14 when piston rod 7 moves to the 
left in that Figure. This places helical compression spring 29 in a 
compressed condition. 
In a similar manner, as piston rod 7 moves toward the right from its 
position in FIG. 3, shoulder 31a at the left end of intermediate reduced 
portion 12 of piston rod 7 will push against washer 30a, which will then 
push helical compression spring 29 to the right against washer 30b, and 
this will push washer 30b against end portion 14b of slide valve 14. As 
left-hand shoulder 31a continues to move to the right in FIG. 3, helical 
compression spring 29 will be placed in a compressed condition in the same 
way as shown in FIG. 2 for movement of piston rod 7 to the left. 
In the preferred embodiment of this invention shown in FIGS. 1-3, third 
actuator 33 is positioned in the longitudinal center of intermediate 
reduced portion 12 of piston rod 7. Third actuator 33 has a diameter 
larger than the rest of intermediate section 12, but smaller than the 
inside diameter of helical compression spring 29 so that it can fit 
concentrically within the spring. 
In addition, actuator 33 has an outside diameter larger than the inside 
diameter of each force-transmitting washer 30, each of which (as mentioned 
above) has an outside diameter larger than the inside diameter of end 
portions 14a and 14b of slide valve 14. It follows from these dimensions 
that as third actuator 33 is carried to the left by piston rod 7 to abut 
against left-hand washer 30a, that washer will be pushed to the left from 
its position in FIG. 1 to its position in FIG. 2, and then still farther 
to the left to apply an axially directed force against end portion 14a of 
slide valve 14. 
As piston rod 7 continues to the left from its position shown in FIG. 2 and 
the force exerted by third actuator 33 on washer 30a is applied to end 
portion 14a of slide valve 14, the same axially directed force is 
transmitted to the other end of the slide valve, where it is exerted on 
spherical locating balls 32 engaged in groove 16b of the holding mechanism 
for the slide valve. The spring loading of spherical balls 32 is selected 
so that the magnitude of the axially directed force required to release 
the engagement of the spherical balls with groove 16b is substantially 
less than the axial force exerted by third actuator 33 as piston rod 7 
moves to the left in FIGS. 1 and 2. In other words, the force directed to 
the left by third actuator 33 is substantially greater than the force that 
is established, or predetermined, as the force necessary to release 
holding means 16b/32. 
As a result, the force supplied by third actuator 33 breaks the engagement 
of locating elements 32 with index groove 16b, and causes the spherical 
balls to slide up on land area 16c between index grooves 16b and 16a as 
the slide valve starts to move to the left in FIG. 2. 
At this moment, the force exerted by compressed helical compression spring 
29 takes over, and immediately pushes slide valve 14 farther to the left, 
until the outer end of end portion 14a strikes end wall 13a of chamber 13. 
At this time, slide valve 14 occupies the position shown in FIG. 3, and at 
the other end of the slide valve spherical balls 32 have slid to the right 
across land area 16c into index groove 16a. This position of the slide 
valve shown in FIG. 3 is its first air inlet position, in which the slide 
valve connects air inlet port 24 to forward stroke conduit 4, and connects 
return stroke conduit 5 to discharge port 25. These connections 
immediately reverse the direction of movement of reciprocating piston rod 
7, and cause it to move to the right, as it is already doing in the 
position shown in FIG. 3. 
When the piston rod has moved far enough to the right from the position it 
occupies in FIG. 3, third actuator 33 will push force-transmitting washer 
30b against end portion 14b of slide valve 14 to break the engagement of 
holding means 16a/32. The force exerted by compressed helical compression 
spring 29 then immediately takes over and pushes slide valve 14 farther to 
the right, until end portion 14b is stopped by end wall 13b of chamber 13. 
This sequence of events continues as reciprocating piston rod 7 moves back 
and forth within control casing 6 and pneumatic cylinder 1, first 
performing its forward stroke, then its return stroke, then again its 
forward stroke, and so on. 
In other words, third actuator 33 functions as a means for releasing 
holding means 16a/32 or 16b/32, respectively by applying to slide valve 14 
an axially directed force of at least the above mentioned predetermined 
miniumum magnitude, first in one direction and then in the opposite 
direction, as reciprocating piston rod 7 moves alternately through its 
forward stroke and then through its return stroke. 
Intermediate Air Passages Within Control Casing Adjacent Slide Valve 
The connections referred to above that are shown in FIG. 3 between forward 
stroke conduit 4 and air inlet port 24 on the one hand, and return stroke 
conduit 5 and air discharge port 25 on the other, are provided by the 
interaction between (1) air channeling grooves 26, 27 and 28 on the 
external surface of slide valve 14 and (2) the inner portion of control 
casing 6 that in this embodiment is formed of a pile 18 of a repeating 
series of three elements 19, 20 and 21. These three elements are an 
annular stabilizing disk 19, an annular packing ring 20, and an annular 
spacing ring 21. 
As seen in cross section in FIG. 1 (for example, at the left end of slide 
valve 14), annular stabilizing disk 19 is flat on one side, and has a low 
annular molding on the other side that engages an annular depression on 
the surface of the adjoining packing ring 20. Stabilizing disk 19 is 
preferably made of metal or a similar strong, stiff material. Packing ring 
20 is formed of resiliently compressible plastic or rubber, and protrudes 
slightly in the inward radial direction with respect to stabilizing disk 
19 and spacer 21. Spacer 21 is made of a suitable hard plastic material, 
and has a low annular molding on one side that engages an annular 
depression on the surface of the adjoining packing ring 20. On the other 
side of the spacing ring, duct spacers 22 (which for clarity are shown 
broken away in FIGS. 1-3) protrude in the axial direction to the adjacent 
stabilizing ring 19. This partially fills the space between the spacing 
ring and the adjacent stabilizing ring, and forms intermediate air 
passages 18a through 18e, which are of generally annular shape and extend 
around slide valve 14 within control casing 6. 
Pile 18 of a repeating series of three elements 19, 20 and 21 is shown in 
an enlarged, partially exploded, view in FIG. 4. Intermediate air passages 
18a, 18b and 18c are shown on the left-hand side of the Figure. When the 
exploded stabilizing ring 19, packing ring 20 and spacing ring 21 are 
re-assembled, intermediate air passages 18d and 18e will be formed where 
indicated. 
In the exploded portion of the Figure, stabilizing ring 19 is shown with 
annular molding 19a on one side, and packing ring 20 is shown with annular 
depression 20a on one of its surfaces. The opposite side of packing ring 
20 has a similar annular depression. Spacing ring 21 has an annular 
molding on its opposite side that engages depression 20a on packing ring 
20 when these elements are assembled in their operative positions. 
As will be seen, in the assembled pile 18 projections 22 on each spacing 
ring 21 extend to the adjacent stabilizing ring 19 to form intermediate 
air passages 18a-18e of generally annular shape. 
In FIGS. 1-3, projections 22 are all shown with their midportions in 
phantom, to emphasize that most of the space between adjacent stabilizing 
ring 20 and spacing ring 21 is (as best seen in FIG. 4) entirely open. 
The final ring 21' on the right-hand side of FIG. 4 in the position of a 
spacing ring, but carries no spacing projections 22 and simply performs a 
stabilizing function. For this reason it is preferably made of metal or a 
similar strong, stiff material. 
In addition to forming intermediate air passages 18a-18e, the inner edges 
of the of assembled pile 18 of repeated series of three elements 19, 20 
and 21 may be considered to form together the major part of the inner wall 
of slide valve-receiving chamber 13. Or, alternatively, assembled pile 18 
of elements 19, 20 and 21 may be thought of as comprising in the aggregate 
what may be called a "liner" or a "sleeve" that is interposed between 
inner wall 6b of control casing 6 and piston slide valve 14. However they 
are characterized, elements 19, 20 and 21 form, as will be described in 
more detail below, a side valve-receiving chamber within control casing 6. 
Interconnection of Three Slide Valve Grooves With Intermediate Air Passages 
It is through the interconnection of the above mentioned air channeling 
grooves 26, 27 and 28 with intermediate air passages 18a through 18e --as 
the slide valve is caused to move back and forth within chamber 13 as 
described above--that the full force of the compressed air entering inlet 
port 24 is directed against side 2a or side 2b, as the case may be, of 
piston 2. As pointed out above, when the slide valve is in its first air 
inlet position, it connects air inlet port 24 to forward stroke conduit 4 
and connects return stroke conduit 5 to air discharge port 25. When the 
slide valve is in its second air inlet position, the reverse is true. 
Middle air channeling groove 27 on slide valve 14 is wider than end grooves 
26 and 28. As will be seen from FIGS. 1 and 3, middle groove 27 is 
connected at all times--through annular shaped intermediate air passage 
18c--to air discharge port 25 in the walls of control casing 6. It will 
also be seen that each one of grooves 26 and 28, at the ends of the series 
of three air channeling grooves, is connected at all times--through 
connecting passageway 24a and from there through annular shaped 
intermediate air passages 18a and 18e, respectively--to air inlet port 24. 
The shifting back and forth of slide valve 14 within slide valve-receiving 
chamber 13 that is described above determines, through the respective 
positions of grooves 26 and 28, whether forward stroke conduit 4 is 
connected through air passages 18d and 18e with inlet port 24 (FIG. 3), or 
whether it is return stroke conduit 5 that is connected through air 
passages 18b and 18a with the air inlet port (FIGS. 1 and 2). 
Groove 28 at the right-hand end of the three air channeling grooves 
connects forward stroke conduit 4 and air inlet port 24 in the manner just 
described when slide valve 14 is in its first air inlet position (FIG. 3). 
This connection introduces the full pressure of the compressed air 
supplied at inlet port 24 to side 2a of piston 2, which immediately causes 
the piston to start its forward stroke. When the slide valve is in its 
second air inlet position, right-hand air channeling groove 28 remains 
connected with air inlet port 24, but is disconnected from forward stroke 
conduit 4 (FIGS. 1 and 2). This disconnection blocks the compressed air 
from applying pressure any longer to side 2a of the piston. 
In a similar manner, air channeling groove 26 at the left-hand end of the 
series of three grooves connects return stroke conduit 5 and air inlet 
port 24 when slide valve 14 is in its second air inlet position (FIGS. 1 
and 2). This connection introduces the full pressure of the compressed air 
from the air inlet port to side 2b of piston 2, which causes the piston to 
immediately reverse its direction of movement and start its return stroke. 
When the slide valve is in its first air inlet position, groove 26 remains 
connected with inlet port 24, but is disconnected from return stroke 
conduit 5 (FIG. 3). The compressed air is thus blocked off from side 2b of 
the piston. 
Just as with air inlet port 24, whether air discharge port 25 is connected 
with forward stroke conduit 4 or with return stroke conduit 5 is 
determined by the position of slide valve 14 within slide valve-receiving 
chamber 13, and the resulting position of central air channeling groove 27 
of the slide valve with respect to the intermediate air passages in pile 
18. As will be seen from FIG. 3, when the slide valve has been pushed to 
the left end of chamber 13 by the action of helical compression spring 29, 
it is return stroke conduit 5 that is connected, through air passage 18b 
and central air passage 18c, with the discharge port. This connection 
allows air to flow from side 2b of piston 2, as the piston moves to the 
right, out of pneumatic cylinder 1 through return stroke conduit 5, 
intermediate air passage 18b, annular air channeling groove 27, 
intermediate air passage 18c, and finally out of discharge port 25. 
As is seen in FIG. 1, when the slide valve has been pushed to the right in 
chamber 13, it is forward stroke conduit 4 that is connected, through air 
passage 18d and central air passage 18c, with the discharge port. This 
connection allows air to flow from side 2a of piston 2, as the piston 
moves to the left, out of pneumatic cylinder 1 through forward stroke 
conduit 4, intermediate passage 18d, annular air channeling groove 27, 
intermediate passage 18c, and finally out of discharge port 25. 
(If the compressed air that flows as described in the two immediately 
preceding paragraphs is allowed to exit freely from discharge port 25, it 
will create an uncomfortably high noise level. To reduce the noise level, 
sound absorber 25a is provided in air discharge port 25.) 
Slide Valve Grooves And Intermediate Air Passages Confine Air To Defined 
Paths 
One of the most important features of the air-operated pump of this 
invention, as exemplified by the embodiment being described, is the 
cooperation of air channeling grooves 26, 27 and 28 on piston valve 14 
with intermediate air passages 18a through 18e, and with the inner wall 6b 
of control casing 6, to confine the flow of air into and out of the 
control casing solely to the restricted paths that have just been 
discussed. Depending upon whether the slide valve is in its first or 
second air inlet position, certain of the intermediate air passages, 
together with a selected plurality of the grooves on the slide valve, form 
an air entry path leading from air inlet port 24 to one side or the other 
of compressed air piston 2, and an associated air exit path leading from 
the other side of the piston to air discharge port 25. 
In this embodiment, when the slide valve is in its first air inlet position 
(FIG. 3), pile 18 of the repeating series of elements 19, 20 and 21 forms 
one set of annular, substantially airtight, intermediate air passages 
18e/18d and 18b/18c. Annular intermediate air passages 18e and 18d, with 
annular air channeling groove 28 between them, define a first air entry 
path within control casing 6 that leads from air inlet path 24 to forward 
stroke conduit 4. At the same time, annular intermediate air passages 18b 
and 18c, with annular air channeling groove 27 between them, define a 
first air exit path within the control casing that leads from return 
stroke conduit 5 to air discharge port 25. 
When the slide valve is in its second air inlet position (FIGS. 1 and 2), 
elements 19, 20 and 21 form another set of annular, substantially 
airtight, intermediate air passages 18a/18b and 18d/18c. Annular passages 
18a and 18b, with annular air channeling groove 26 between them, define a 
second air entry path within control casing 6 that leads from air inlet 
port 24 through connecting passageway 24a to return stroke conduit 5. 
Similarly, annular intermediate air passages 18d and 18c, with annular air 
channeling groove 27 between them, define a second air exit path that 
leads from forward stroke conduit 4 to air discharge port 25. 
The manner in which inner wall 6b of control casing 6 cooperates with the 
air channeling grooves on the slide valve and with the intermediate air 
passages, as just described, to shield the interior of the piston slide 
valve from the air flow through control casing 6 is as follows: Pile 18 of 
elements 19, 20, and 21, which provides a slide valve-receiving channel 
within the control casing, has an inwardly facing surface that makes at 
all times an annular, substantially airtight, slidable contact with the 
outer surface of opposite end portions of the slide valve at 14d and 14e. 
Likewise, pile 18 has an outwardly facing surface that makes at all times 
an annular, substantially airtight contact with inner wall 6b of the 
control casing at 18f and 18g adjacent each of the opposite ends of the 
slide valve. The four contacts at 14d, 14e, 18f and 18g are at all times 
located farther axially from the central portion of the slide 
valve-receiving channel tan are (1) the channeling grooves an the slide 
valve, (2 ) all the intermediate air passages, and (3) all opening sin the 
inner wall of the control casing that lead away from pile 18 of series of 
elements 19, 20 and 21. 
The four annular, substantially airtight contacts at 14d, 14e, 18f and 18g 
that have just been described are arranged and adapted to isolate the 
interior space within the piston slide valve (1) from compressed air that 
enters the air inlet port and passages through one of the first and second 
air entry paths referred to above, and (2) from outflowing air at a lower 
pressure that passes through the air exit path that is associated with 
said one air entry path and from there out through the air discharge port. 
The space occupied by the slide valve releasable holding means, which in 
this embodiment comprises indexing grooves 16a and 16b, helical 
compression springs 17 and spring-biased spherical balls 32, is likewise 
isolated from the indicated air flow in and out of control casing 6. 
(packing rings 9, shown toward the left in FIGS. 1-3 and toward the right 
in FIGS. 2 and 3, protect the interior space within the slide valve from 
air that might otherwise flow directly out of pneumatic cylinder 1 into 
the space within the valve, or into the space from its other end.) 
Confining the air flow to restricted flow paths as just described provides 
two important advantages that are not available in the prior art. The 
first of these is that compression spring 29 within the interior of the 
slide valve, and compression springs 17 in the releasable holding means 
for the slide valve, are not subject to long term damage by being 
repeatedly exposed to bursts of compressed air, or to the lesser long term 
damage that it is believed can be caused by repeated sudden exposure to 
the air that exits from the device of this invention at lower pressure. 
Second, the force exerted by the compressed air on alternate sides of 
reciprocating piston 2 is not diluted by expansion into extraneous spaces, 
or by possible leakage of the high pressure air through various 
less-than-airtight parts of the mechanism. With the full pressure of the 
compressed air maintained in the air-operated lubricant pump of this 
invention, the reversal in the direction of movement of the reciprocating 
piston rod is significantly faster and more reliable than was possible 
with any prior art device. 
Because of the above described action of helical compression spring 29, and 
the resulting alternate connection and breaking of the connection between 
air inlet port 24 and the opposite sides 2a and 2b of pneumatic piston 2 
just detailed, the full force of the compressed air that is introduced 
into this mechanism is automatically--and immediately--available to 
reverse the direction of movement of reciprocating piston rod 7 from its 
forward movement or return movement at the exact moment the engagement of 
holding means 16a/32 or 16b/32, respectively, is released and compression 
spring 29 snaps slide valve 14 from one of its-air inlet positions to the 
other. 
This result is enhanced, as has just been explained, by the fast that the 
flow of air through the mechanism of this invention is kept out of 
extraneous spaces within the mechanism, and away from various 
less-than-airtight parts of the mechanism. 
SPRING DIMENSION 
This embodiment with third actuator means 33, shown in FIGS. 1-4 and 
described above, is the preferred form of the device of the present 
invention because in this embodiment the force required to release the 
holding means (either 16a/32 or 16b/32) is produced solely by the third 
actuator, as piston 2 moves in response to the compressed air introduced 
into pneumatic cylinder 1. This means that it is never necessary to 
compress compression spring 29 completely in order to apply the requisite 
releasing force to end portion 14a or 14b of slide valve 14, as is 
necessary when an axial force exerted by actuator 31a or 31b through the 
completely compressed spring is relied on to release the holding means. 
When third actuator 33 provides the necessary releasing force, compression 
spring 29 need be compressed only far enough that when the holding means 
is released the slide valve will be immediately moved from one of its air 
inlet positions to the other. The fact that the spring need never be 
completely compressed of course adds greatly to the life of the spring. 
In order to ensure that compression spring 29 in this embodiment is never 
put in its fully compressed condition, its length when fully compressed 
must be (as will be seen from FIG. 2) less than (1) the length 33a of 
third actuator 33, plus (2) the second predetermined distance 34 between 
member 33 and an adjacent shoulder 31 (such as shoulder 31b), less (3) the 
thickness of a force-transmitting washer 30 (such as washer 30b). 
In order to exert the desired axial force to move spherical locating ball 
32 from one of the index grooves 16a and 16b across land area 16c to the 
other index groove immediately after the holding means is released as 
described above, compression spring 29 in its fully relaxed condition must 
be (as also seen from FIG. 2) somewhat longer than the sum of (1) length 
33a, plus (2) distance 34, less (3) the thickness of one of said 
force-transmitting washers (such as washer 30b). A better length of the 
helical compression spring in its relaxed condition is still longer, by an 
amount at least equal to the first predetermined distance between the 
center lines of first and second index grooves 16a and 16b. A preferred 
length for the compression spring in its fully relaxed condition (which is 
somewhat less than is illustrated in FIGS. 1 and 3) is just less than the 
distance between shoulders 31a and 31b, minus the thickness of two 
force-transmitting washers 30. 
Other Illustrative Embodiments 
Helical Compression Spring Releases Piston Slide Valve Holding Means 
If desired, third actuator 33 may be omitted under certain circumstances in 
which helical compression spring 29 can, acting alone, apply an axially 
directed force of a magnitude equal to or greater than the predetermined 
minimum magnitude required to release spherical locating balls 32 from 
index groove 16a or 16b in FIG. 1. As will be understood from FIG. 2, in 
the absence of third actuator 33, when piston rod 7 is on its return 
stroke it will continue its movement to the left until compression spring 
29, acting through force-transmitting washer 30a, pushes slide valve 14 to 
the left within slide valve-receiving chamber 13 to bring end portion 14a 
of the slide valve against end wall 13a of the chamber. 
Similarly, in the absence of third actuator 33, when reciprocating piston 
rod 7 is on its forward stroke the movement of the rod to the right in 
FIG. 3 will continue until shoulder 31a, acting through force-transmitting 
washer 30a, pushes the left-hand end of compression spring 29 far enough 
to the right that the force applied against end portion 14b of slide valve 
14 will disengage spherical balls 32 from index groove 16a, and move the 
slide valve to the right-hand end of chamber 13 and thereby move the 
spherical balls into engagement with index groove 16b. 
Except when the force required to release holding means 16a/32 or 16b/32 is 
relatively low, it will usually be necessary with this embodiment that the 
helical compression spring be pushed by a shoulder of the moving piston 
rod into its completely compressed condition, with immediately adjacent 
circular elements of the helical spring in full contact with each other. 
In this condition, the spring will essentially act as a solid hollow 
cylinder, and can transmit to end portion 14a or 14b of slide valve 14 
whatever axially directed force is required to release holding means 
16a/32 or 16b/32 at the opposite end of the slide valve. (The device 
discussed below of which FIG. 6 is a fragmentary view is one form of this 
embodiment in which no third actuator means is included.) When the 
engagement of spherical locating balls 32 with an indexing groove is 
broken, the helical spring will immediately start to expand to return to 
its normal uncompressed state, thereby moving the spherical balls out of 
one indexing groove, across the land area between the two indexing 
grooves, and into engagement with the other groove. 
When this second embodiment under discussion is utilized, it is 
advantageous to flatten the two sides of the wire comprising the helical 
compression spring that come into contact with each other when the spring 
is fully compressed. FIG. 5 is a fragmentary sectional view of such a 
helical compression spring. Sides 35 and 36 on immediately adjacent 
circular elements of the helical spring are flattened, so that when the 
spring is completely compressed one flat surface will abut the other. This 
configuration will strengthen the helical spring when it acts, as 
described above, as a solid hollow cylinder when it has been put in its 
fully compressed condition. 
Another expedient to strengthen the helical spring when in its fully 
compressed condition is to select the diameter of the intermediate reduced 
section of the reciprocating piston rod and the inside diameter of the 
cavity within the slide valve so as to confine the helical compression 
spring rather closely. As will be seen, this will tend to keep the several 
circular elements that comprise the helical spring in alignment. It is 
also advantageous to fabricate the helical compression spring of an alloy 
that is likely to minimize both the metal fatigue and the impact damage 
that full compression of the spring may tend to produce. 
This second embodiment can be used in two situations. It may be used, for 
example, in a situation in which it is acceptable to have a holding means 
for the piston slide valve that can be released by a relatively lower 
axially directed releasing force. In such case, the impact of actuator 31a 
or 31b on the fully compressed helical spring would not be so great, and 
could therefore be better tolerated by the spring. Second, if the 
acceptable releasing force is low enough, it may be possible to use a 
compression spring of sufficient stiffness that it will actually not need 
to be fully compressed at any time, but in a partially compressed 
condition can exert the necessary releasing force itself without having to 
rely on the first or second actuator 31a or 31b acting through a fully 
compressed spring. 
Force-Transmitting Washers Omitted 
In a third embodiment, force-transmitting washers 30a and 30b may be 
omitted, if desired, provided the dimensions of the intermediate reduced 
portion of the reciprocating piston rod and the cooperating inner wall of 
the annular cavity within the piston slide valve are properly selected. 
FIG. 6 is a fragmentary sectional view of such an embodiment. 
Piston slide valve 14' has air channeling, grooves 26' and 27' on its 
external surface Helical compression spring 29' is slidably held between 
elongated annular cavity 14c' of the slide valve and reduced portion 12' 
of reciprocating piston rod 7'. 
Sides 35 and 36 on immediately adjacent circular elements of the helical 
spring are flattened, so that in the completely compressed condition shown 
in FIG. 6 one flat surface abuts another. In this completely compressed 
condition, helical spring 29' acts as a solid hollow cylinder. Shoulder 
31b' has pushed compression spring 29' to the left in FIG. 6 against end 
portion 14a' of the slide valve until the spring is fully compressed. 
In this third embodiment, the diameter of reciprocating piston rod 7' is 
preferably just less than the inside diameter of end portion 14a' of slide 
valve 14'. The difference between the diameter of piston rod 7' and the 
diameter of its reduced portion 12' is substantially equal to the 
difference between the inside diameter of end portion 14a' and the inside 
diameter of elongated angular cavity 14c' of the slide valve. The 
difference just referred to between the indicated diameters is slightly 
more than one-half the diameter 37 of the individual circular elements 
that comprise helical compression spring 29', which allows the compression 
spring to slide freely within cavity 14c' and still have its individual 
circular elements held in substantial alignment with each other as are 
pushed into their fully compressed condition. 
Comparison of Various Embodiments 
The additional embodiments of the mechanism of this invention described in 
this section of the specification require fewer mechanical parts than, but 
operate generally in the same manner as, the preferred embodiment 
described in the preceding section. The results with the various 
embodiments described are generally similar, but the preferred embodiment 
of FIGS. 1-4 has certain distinct advantages. 
In the preferred embodiment there is less wear on, or damage to, the 
helical compression spring because it is never fully compressed. Because 
of the construction of the preferred embodiment, there is less need to be 
concerned about maintaining the accurate alignment of the individual 
circular elements of the helical compression spring. The manufacture of 
the preferred embodiment is simpler because the tolerances in the 
fabrication of various interfitting parts are not so close as they are in 
the second and third embodiments. 
Because third actuator 33 is present in the preferred embodiment, the 
minimum force required to release the slide valve holding means can be 
greater than when actuator 33 is not included, since release is effected 
by a force supplied by the third actuator as a completely and permanently 
solid member. This makes it possible to have a higher spring loading on 
the spring-biased holding means, resulting in increased reliability of the 
indexing engagement of the slide valve. Finally, selection of a helical 
compression spring having the proper composition and cross-sectional shape 
of the individual circular elements of the spring is a significantly less 
critical matter when third actuator 33 is present. 
METHOD OF ASSEMBLY 
Control casing 6 of the preferred embodiment shown in FIGS. 1-3 and 
described above, and the elements contained in the casing, can be easily 
and efficiently assembled in any of several ways, of which the following 
is one example. 
First, stabilizing rings 19, packing rings 20 and spacing rings 21 that 
make up pile 18 can be positioned on slide valve 14. 
Second, reciprocating piston rod 7 and the elements carried by it can be 
assembled by assembling washer 30a, helical compression spring 29, and 
washer 30b on reduced portion 12 of the piston rod. The reduced portion 
can then be bolted to the left-hand portion of piston rod 7. 
Third, piston rod 7 with the assembled parts mounted on it as just 
described can be inserted into the main body of control casing 6 and 
positioned within the opening in pile 18. Right-hand end portion 14b/15 of 
the slide valve can then be slid onto the right-hand portion of piston rod 
7. This portion of the piston rod can then be bolted to reduced portion 
12, and part 14b/15 can be screwed into engagement with the main body of 
the slide valve. 
Fourth, flanged neck 11 can then be bolted to the right-hand end of control 
casing 6, to complete the assembly of these members. 
Finally, locating elements 32 can be inserted into access ducts 17b on 
flanged neck 11, and spring loading members 17a adjusted to hold the 
locating elements in releasable engagement with either indexing groove 16a 
or 16b. 
Other ways to assemble the disclosed mechanism of this invention will be 
apparent to those skilled in the art. 
While the present invention has been described in connection with the best 
mode presently contemplated by the inventor for carrying out his 
invention, the preferred embodiments described and shown are for purposes 
of illustration only, and are not to be construed as constituting any 
limitation of the invention. Modifications will be obvious to those 
skilled in the art, and all modifications that do not depart from the 
spirit of the invention are intended to be included within the scope of 
the appended claims.