US2905020A - Device for use in connection with fuel injection pumps for adjusting the delivery thereof - Google Patents

Description

Sept. 22, 1959 K. ZIESCHE ETAL DEVICE FOR USE IN CONNECTION WITH FUEL INJECTION PUMPS FOR ADJUSTING THE DELIVERY THEREOF 5 Sheets-Sheet 1 Filed Feb. 20, 1956 FIG. 2

FIG. I

I lll lll h Qg AI Sept. 22, 1959 K. ZIESCHE ETAL 2,905,020

DEVICE FOR USE IN CONNECTION WITH FUEL INJECTION PUMPS FOR ADJUSTING THE DELIVERY THEREOF Filed Feb. 20, 1956 s Sheets-Sheet 2 Sept. 22, 1959 K. ZIESCHE ET AL 2,905,020

DEVICE FOR USE IN CONNECTION WITH FUEL INJECTION PUMPS FOR ADJUSTING THE DELIVERY THEREOF 5 Sheets-Sheet 3 Filed Feb. 20, 1956 INVENIGPS fur) O W n/a United States Patent'O DEVICE FOR USE IN CONNECTION WITH FUEL INJECTION F311 ADJUSTING THE DE- LIVERY IIFHEREGF 'Kurt Ziesche, Koln-Dunnwald, Anton Kobus, Koln-Mnlhelm, and Oswald May, Bonn, Germany, assign'ors to KIiickner- HumholdnDeutz, Akfie'ngesellschaft, Kohl, *Germany The present invention relates to fuel injection pumps, and more particularly, to a device for use in connection with such pumps for adjusting the delivery thereof in connection with the starting of an internal combustion engine Su'ch devices which are adjustable in such a manner that the delivery for the starting period is in excess of the 'full load delivery during the normal operation of the internal combustion engine equipped with such fuel injection pump must be designed in such a manner that it will safely prevent the adjustment of the starting fuel quantity while the engine is running. 'The reason for this consists in that during normal operation of the i engine, the engine cannot process the said starting fuel quantity and therefore causes the exhaust to smoke excessively.

The heretofore known adjusting devices used in connection with fuel injection pumps comprise an abutment connected to a control rod, which abutment detei mines the full load delivery of the injection pump during normal operation of the engine. Following the turning off of the engine orprior to the starting of the engine, the said abutment is made ineffective by actuating means out- "side the injection pump',.'but after a minor movement of the control rod in the direction toward a reduced charge, the said abutment automatically becomes effective again.

It is, therefore, an object of the present invention to provide adjusting means associated with a -fuel injection pump, which will allow the "adjustment of a starting fuel delivery but will be considerably simpler and more reliable than the heretofore known devices of this type.

It is another object of invention to provide adjusting means of the type set forth in the preceding paragraphs which, while preventing the adjustment of the fuel pump for delivery of a starting quantity of fuel while the engine is running, will be so simple that it may also be em loyed with fuel injection pumps for engines of a low number of cylinders, for instance, for one or two cylinder engines.

It is still another object to provide adjusting means of the type set forth in the preceding paragraphs, which will make it impossible, even when using certain tools from the outside of the adjusting means to effect an'adjus'tment for delivering an increased starting quantity of fuel while the engine is running.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which Fig. l is a longitudinal se'io'n through a one cylinder fuel injection pump according to the invention, said sec tion being taken along the line I-I of Fig. 2.

Fig. '2 is a partial section through Fig. 1 taken along the line HII thereof.

"Fig; 3 is a section taken along the line IIIIII of Fig. 2 but with a somewhat modified abutment element.

Fig. 4 is a modification of an arrangement according to the present invention and represents a section taken along the line IV-IV of Fig. 5..

Fig. 5 is a section along the line V-V of Fig. 4.

7 General arrangement The adjusting deviceaccording to the present invention consists primarily in that a bending .is employed as stationary abutment which extends parallel to the control rod at leastswithin the range of movement of theabutment connected to the control nod. Said lastmentioned abutment in addition to being provided with an abutment surface for engagement by the of the nonbent bending spring is provided an aperture, while :an actuating member operable "from the outside of the injection pump "is adapted so to actuate the bending spring that its tip is deflected into a position within the :area of said apertune to thereby initiate the adjustment of the pumpufor delivering the increased quantity of. fuel desired .for starting the engine. As actuating member, there may, for instance, be employed a bolt which :is displaceably mounted in the casing and is movable perpendicular to the longitudinal extension of the bending spring. The arrangement is such that the inner end .face of the bolt engages the bending spring. In its most simpleforrm, a spring wire may he used as bonding spring. For .pur poses 'of adjusting the admissible rfull load fuel delivery of the pump .for normal operation, the spring. wire is connected to an adjusting screw screwed into easing of the pump.

According to a further development of the invention, the abutment surface on the control rod is so arranged that a. sheet metal plate is connected to a flattened portion of the control rod in :such a manner that the said plate is parallel to the axis of the control rod. 'IDhe said sheet meta-lp-late is provided with an ear having its major surface located in a plane perpendicular the longitudinal axis 'of the control rod. It is the sunface of the :said earwhich serves as abutment surface. When providing the said sheetnietal plate with a second ear spaced from and parallel to said first ear, the adjustment of the delivery for starting the engine will beirn'ade impossible wh-ile the internalcombustion engine is running.

Stmcmr'al arrangement Referring to the drawings in detail, and Figs. 1 and 2 thereof in particular, the fiuel pump shown therein com prises in customary manner a casingsl, a'pump cylinder 2, a pressure valve 3 an'da piston 4 reciproeable in said pump cylinder. .For purposes of varying the quantity of fuel to be injected, the piston 4 .is notat-ably adjustable. Depending on the rotative position of the piston 4,, the ,efiective delivery stroke is completed earlier or later by sliding of the inclined control slot 5 over the connectirrg bore leading to the overflow passage of -the pump. The rotative or angular adjustment of the pump piston 4 .is effected by means of a control rod 6 which is dis placeably mounted in the casing 1. For each cylinder, the control rod :6 has screwed thereinto a screw 7 with ball head 8. The screw 7 with ball head 8 extends into an axial groove of the piston 4. The drive of the pump piston 4 :is effected through ia push rod with roller 9 to be actuated by the :cam shaft (not shown? of the internal combustion engine to be driven.

A sheet metal plate 1'0 is connected to the control rod by means of the said screw 7. This sheet metal plate 1 0 has two ears 11 and 12 which, while being substantiallyparallel to each other extend in planes: directed substantially perpendicular to the axis of the control rod :6. That surface of the ear .1 2 which is arranged on that side of the sheet metal plate 10 which faces the idling position of the control rod 6 acts as full load abutment in cooperation with a spring wire 13. The said spring wire 13 is connected to an adjusting screw .14. screwed into the casing 1. Directly adjacent the bending edge .15. of the ear 12,, the latter is provided with a rectangular cutout or window 16. For purposes of adjusting the quantity of fuel desired for starting the engine, the tip of the spring wire 13 which normally by abutment against the ear 12 limits the full load quantity of fuel during normal operation of the engine, is bent or deflected in front of the window 16. This deflection is effected by means of a bolt 17 mounted in the casing 1. It will be appreciated that if the tip of the spring wire :13 is deflected into a position in front of the window 16, the spring 18 acting upon the control rod 6 will then pull the latter outwardly so that the car 12 moves toward the left with regard to Fig. 1 over the spring wire 13, thereby causing the ball head 8 engaging the groove 4' to turn or angularly adjust the piston 4 and thereby the slot 5 in the direction for causing the pump to deliver a starting quantity of fuel in excess of the normal full load quantity of fuel during the ordinary operation of the engine. The bolt 17 is provided with a pin 20 extending in a direction transverse to the axis of the bolt 17. The said pin 20 limits the outward movement of the bolt 17, which latter, by means of a spring 23, is continuously urged toward the outside. The movement of the ear 12 over the wire spring 13 is limited by engagement with a sleeve 19 surrounding the wire spring 13 and mounted stationarily in the casing for the fuel pump.

The device of Figs. 1 and 2 is characterized by great simplicity and due to its few parts and small size may, as shown in the drawing, be employed in connection with a one cylinder injection pump.

The operation of the device of Figs. 1 and 2 is as follows. It may be assumed that the internal combustion engine equipped with a fuel pump and the control system of the present invention is at a standstill. The control rod 6 will then occupy the position shown in Figs. 1 and 2 in which the ear 12 abuts the adjacent end of the wire spring 13. The control rod 6 which is operatively connected to the governor of the internal combustion engine pulls the control rod 6 into the position shown in Figs. 1 and 2 when the internal combustion engine is at a standstill. The position of control rod 6 as shown in Figs. 1 and 2 corresponds to the full load filling.

For starting the internal combustion engine, a filling or fuel volume in excess of said full load filling is required. T his starting filling is adjusted by pressing upon the knob of bolt 17. Bolt 17 will then press against the wire spring 13 and deflect the same laterally until the wire spring 13 comes within the range of the rectangular window 16. In this instance, the control rod is released so that it will be able to move in a direction to increase the filling. The starting filling thus obtainable is determined by the adjustment of the tube 19 against which car 12 will abut.

It will thus be obvious that after the operator has actuated bolt 17, the filling required for the starting of the internal combustion engine will automatically adjust itself so that the internal combustion engine by means of its starting mechanism can be started. As soon as the engine has started, it has the tendency in View of the excssive starting filling to assume a high speed. This tendency is opposed by the governor of the engine which governor then moves control rod 6 in a direction to reduce :the filling and does so until it occupies a position which corresponds to its position during the idling of the engine. During the last mentioned readjustment of control rod 6, window 16 again releases the wire spring 13 so that the latter will again occupy the position shown in Figs. 1 and -2 and thereby determine the full load filling. When the internal combustion engine is under load, the governor can displace control rod 6 only in a direction to increase the filling until the ear 12 abuts the free end of wire spring 13. v V

Fig. 3 illustrates a simple arrangement which will make it possible to prevent the adjustment of the starting quantity of'fuel while the internal combustion engine associatedwith said pump is already in operation. With the arrangement of Figs. 1 and 2, it would be possible by 4 arresting the bolt 17 in its inwardly pressed position, for instance, by placing a band over said bolt '17 in its inward depressed position, to have the pump continuously deliver the quantity of fuel intended for the starting period only. In order to preventsuch undesired manipu lation, according to Fig. 3, the ear 12a has its end portion 21 bent once more so that the thus formed end surface 22 will be parallel to the sheet metal plate 10a. The length of the end portion 22 in axial direction of the control rod 6a is so selected that the free edge of the end surface 22 engages the bolt 17a as soon as the tip of the wire spring 134: has moved only slightly into the window 16a.

If the operator now arrests the bolt 17a in its inwardly pressed position, the control rod 6a can only to a very minor extent, i.e., until the end surface 22 engages the circumference of bolt 17a be moved beyond the normal permissible full load quantity.

The bolt 17a has associated therewith a withdrawing spring 23a. This spring normally returns the bolt 17a to its outer position when following its pressing inwardly, the tip of the wire spring 13a has entered the window which is provided in the ear 12a and corresponds to the window 16 .of Fig. 2. It will be appreciated that when the bolt 17a is moved outwardly, it is out of the range of movement of the end surface 22 so that the ear 12:: will be pulled over the Wire spring 13a until it abuts the adjacent end surface of the sleeve 19a.

The invention may also be used in connection with fuel injectionpumps which do not have a separate control rod. Such an arrangement is shown, for instance, in

Figs. 4 and 5. The various parts shown in these figures and corresponding to those of Figs. 1 and 2. have been designated with the same reference numerals as in Figs.

:1 and 2 but with the additional character [1.

The one cylinder fuel injection pump shown in Figs. 4 and 5 is equipped with a hydraulic control comprising a control member acted upon by the overflow fuel. The

said control member is represented by a piston 24. The hydraulic control also comprises control springs 25 and a device for adjusting the control by varying the preload upon the springs. The said adjusting device comprises a pin 27 acting upon a spring disc 26, and also comprises a two arm lever 28. (The movements of the control piston 24 are, in order to prevent the transfer of control vibrations or oscillations, conveyed to a two arm lever 30 by means of a leaf spring 29. The two arm lever 30 is The other free end of the lever 30 has connected thereto a bolt 32 with a ball head :33. This ball head, similar to the arrangement of Figs. -l to 3, extends into an axial groove 34 of a bushing 35 connected to the pump piston 4b. Thus, a tilting movement of the lever 30 as a result of a displacement of the control piston 24, will bring about a rotative or angular adjustment of the pump piston 4b. Thelever 30 has a cylindrical bore 36 and a transverse bore 37 extending .transverse to the bore 36. A spring wire 13b extending through bore 37 is connected to an adjusting screw 14b and the tip of the spring wire 13b may be bent or deflected so that it will be in front of the transverse bore 37. In its normal, i.e., unbent position, the tip of the spring Wire 13b engages the oppositely located surface of the cylindrical bore 36 laterally of the transverse bore 37 and thus acts as an abutment for the lever 30 to prevent further tilting movement thereof. This abutment determines the full load quantity of fuel during .the normal operation of the respective internal combustion engine.

For purposes of'adjusting the pump for delivering the starting quantity of fuel, the actuating bolt 38 is against the thrust of the spring 23b moved into the casing and deflects the tip of the spring wire 13b so that itwill be in front of the transverse bore 37. The lever 30 can now tilt further up to its abutment against the abutment screw 39 shown in Fig. 4 and adjusted for the respective starting quantity of fuel. The arrangement also comprises a second abutment screw 40 for adjusting the quantity of fuel for idling of the engine. The bolt 38 carries a manually operable knob 41* and simultaneously serves for turning oif the fuel pump. To, this end, the knob is rotated against the thrust of the spring 23b which also acts as torsion spring; During this movement, the pin 42 extending in a direction perpendicular to the axis of the bolt 38 takes along the lever 30 through the intervention of a pin 43 in the lever 30 so that the lever 30 is moved into position for no delivery.

The arrangement according to Figs. 4 and operates in the following manner. It may be assumed that an internal combustion engine equipped with an arrangement according to Figs. 4 and 5 is in its rest position. In such an instance, lever 30 occupies a position shown in Fig. 4 in which it determines the full load filling for the fuel injection pump; The inner wall of bore 36 of lever 30 will then adjacent bore 37 rest against wire spring 13b. In order to adjust the starting filling for the engine which exceeds the full load filling, wire spring 13b is by means of bolt 38 displaced laterally so that it comes into the range of bore 37. The control spring 25 then by means of piston 24 and spring 29 displaces lever 30 in a direction to increase the filling until lever 30abuts the abutment screw 39. The internal combustion engine can then be started.

After the engine has developed a higher speed, the governor will then effect a return adjustment so that Wire spring 13 will return to its normal position and thereby determine the full load fuel quantity.

In order that similar to the arrangement of Fig. 3 it will. be impossible to adjust the pump for delivering the starting quantity of fuel While the internal combustion engine is running, the arrangement of Figs. 4 and 5 is provided with a plate 44. This plate 44 which is connected to the lever 30 by means of screws or rivets 45 partially covers up the bore 36. The edge 46 of plate 44 faces the bolt 38 and engages the bolt 38 when the latter is pressed inwardly, i.e., at a time when the tip of the wire spring 13 has onlyslightly entered the transverse bore 37. The adjustment of the pump for delivering the starting quantity of fuel will then be possible only afterthe bolt 38 has been released and has moved outwardly.

Bolt 38 is provided with a pin 42 which during rotation of bolt 38 abuts a pin 33 in lever 30; In this way lever 30 may be adjusted for no filling so that the internal combustionengine will be stopped. 4

It is, of course, to be understood that the present invention is, by no means, limited to the particular constructions shown in the drawings, but also comprises many modifications within the scope of the appended claims.

What we claim is:

1. In combination in an adjustable stop arrangement for fuel pumps: a rotatable adjustable member, a casing, a control member mounted in said casing and movable in a first and a second direction opposite to said first direction, means connected to said control member and arranged in operative engagement with said adjustable member to adjust the latter in a first sense in response to a movement of said control member in said first direction and to adjust said adjustable member in an opposite sense in response to a movement of said control member in said second direction, a substantially rigid abutment element carried by said control member, a bendable resilient abutment element mounted in said casing and arranged normally to abut said rigid abutment element to limit the movement of said control member in said first direction, said rigid abutment element being provided with a window adjacent that surface of said rigid abutment element which is normally in abutment with said resilient abutment element, and means reciprocably mounted in said casing and operable to movethe free end of said resilient abutment element inv front of said window to thereby make said resilient abutment element ineffective as abutment and to allow movement of said controlrnember in said first direction beyond its normal position for adjusting said rotatable adjustable member in said first sense.

2. In combination in an adjustable stop arrangement for fuel pumps: arotatable adjustable member, a casing, a control member mounted in said casing and movable in a first and a second direction opposite to saidfirst direction, means connected to said control member and arranged in operative engagement with said adjustable member to rotate the latter in a first sense in response to a movement of said control member in said first direc tion and to rotate said adjustable member in a second sense opposite to said first sense in response to a movement of said control member in said second direction, a substantially rigid abutment element carried by said control member, a bendable resilient abutment element mounted in said casing and arranged normally to abut said rigid abutment element to limit the movement of said control member in said first direction, said rigid abutment element being provided with a window adjacent that surface of said rigid abutment element. which is normally in abutment with said resilient abutmentelement, a bolt member reciprocably mounted in said casing and movable into engagement with said resilient abutment element for moving the free end thereof in front of saidwindow, and resilient means continuously urging said bolt member away from said resilient abutment element.

3; Anarrangement' according to claim 2, in which said resilient abutment element consists of a deflectable bar;

4. In combinationin an adjustable stop arrangement for fuel pumps: rotatable adjustable member, a casing, a control member mounted in said casing and movable in a first and a seconddirection opposite to said first direction, means connected to said control member and arranged inoperative engagement with said adjustable member to rotate the latter in a first sense in response. to a movement of said control member in said first direction and to rotate said adjustable member ina second sense opposite to said first sense in response to a movement of said control member in said second direction, a substantially rigid abutment element carried by said control member, an adjusting screw threadedly engaging saidcasing and accessible from the outside thereof, a bendable resilient abutment element fixedly connected to said adjusting screw and arranged normally to abut said rigid abutment element to limit the movement of saidcontrol member in said firstdirection, said rigid abutment element being provided with a window adjacent that surface of said rigid abutment element which is normally in abutment with said resilient abutment element, and deflecting means reciprocably mounted in said casing and operable to move the free end of said resilient abutment element in front of said window to thereby make said resilient abutmentelement ineffective as abutment and to allow movement of said control member in said first direction beyond its normal position for rotating said adjustable memberin said first sense.

5. In combination in an adjustable stop arrangement for fuel pumps: a rotatable adjustable member; a casing, a control member mounted in said casing and movable in a first and a second direction opposite to said first direction, means connected to said control member and arranged in operative engagement with said adjustable member to rotate the latter in a first sense in response to a movement of said control member in said first direction and to rotate said adjustable member in a second sense opposite to said first sense in response to a movement of said control member in said. second direction, a metal plate connected to said control member and being providedwith an ear normally serving as rigid abutment element to limit the movement of said control member in said first direction, a bendable resilient abutment element mounted in said casing and arranged normally to abut said rigid abutment element, said ear being provided with a window adjacent that surface of said rigid abutment element which is normally in abutment with said resilient abutment element, and means reciprocably mounted in said casing and operable to move the free end of said resilient abutment element in front of said window to thereby make said rigid abutment element ineffective as abutment member and .to allow movement of said control member in said first direction beyond its normal position for rotating said adjustable member in said first sense.

6. An arrangement according to claim 5, in which said Window is arranged directly adjacent the line of intersection of said ear with said metal plate and has a rectangular contour, the larger side of said window being substantially parallel to the direction of movement of said control member and the shorter side of said window being wider than the Width of said resilient abutment element.

7. In combination in an adjustable stop arrangement for fuel pumps: a rotatable adjustable member, a casing, a control member mounted in said casing and movable in a first and a second direction opposite to said first direction, means connected to said control member and arranged in operative engagement with said adjustable member to rotate the latter in a first sense in response to a movement of said control member in said first direction and to rotate said adjustable member in a second sense opposite to said first sense in response to a movement of said control member in said second direction, a metal plate connected to said control member and provided with an ear normally serving as abutment to limit the movement of said control member in said first direction, a bendable resilient abutment element mounted in said casing and arranged normally to abut said rigid abutment element, said ear being provided with a window adjacent that surface of said rigid abutment element which is normally in abutment with said resilient abutment element, said metal plate also being provided with a second ear arranged in spaced relationship to said first ear and provided with a guiding opening, guiding means connected to said casing and extending through said guiding opening, and deflecting means reciprocably mounted in said casing and operable to move the free end of said resilient abutment element in front of said window to thereby make said resilient abutment element ineffective as abutment and to allow movement of said control member in said first direction beyond its normal position for rotating said adjustable member in said first sense.

8. An arrangement according to claim 7, in which that end of said guiding means which faces said first ear is arranged in the path of the latter to limit the movement of said control member in said first direction by engagement with said first ear.

9. In combination in an adjustable stop arrangement for fuel pumps: a rotatable adjustable member, a casing, a control member mounted in said casing and movable in a first and a second direction opposite to said first direction, means connected to said control member and arranged in operative engagement with said adjustable member to rotate the latter in a first sense in response to a movement of said control member in said first direction and to rotate said adjustable member in a second sense opposite to said first sense in response to a movement of said control member in said second direction, a metal plate connected to said control member and provided with an ear having a first section substantially perpendicular to the major surface of said metal plate and having a second section spaced from and substantially parallel to said major surface, a bendable resilient abutment element mounted in said casing and arranged normally to abut the major surface of said metal plate to limit the movement of said control member in said first direction, said metal plate being provided with a window adjacent said first section of said ear, and a reciprocable member reciprocably mounted in said casing and operable to move the free end of said resilient abutment element in front of said Window to allow saidresilient abutment element to enter said window, said second section of said ear being arranged to abut said reciprocable abutment element when said resilient member has just entered said window.

10. In combination in an adjustable stop arrangement for fuel pumps: an adjustable member, hydraulic control means for rotatively adjusting said adjustable member, a casing housing said hydraulic control means, lever means tiltably mounted in said casing and operatively connected to said hydraulic control means to be tilted by the latter, said lever means being tiltable in a first direction opposite to said first direction and a second direction, means connected to said lever means and arranged in operative engagement with said adjustable member to rotate the latter in a first sense in response to a movement of said lever means in said first direction and to rotate said adjustable means in a second sense opposite to said first sense in response to a movement of said lever means in said second direction, said lever means having a first bore therein with the axis thereof perpendicular to the tilting direction of said lever means and also being provided with a second bore transverse to said first bore and leading into said first bore, a bendable resilient abutment element extending through said second bore into said first bore and normally abutting the inner surface wall of said first bore, said resilient abutment element having its. end remote from said second bore fixedly mounted, said first bore also being provided with a window laterally of the axis of said second bore but on that wall portion of said first bore which is faced by the free end of said resilient abutment element, and means reciprocably mounted in said casing and operable to move the free end of said resilient abutment element in front of said window to thereby make said resilient abutment element ineffective as abutment and allow said lever means to tilt toward the fixed end of said resilient abutment element.

11. An arrangement according to claim 10, in which said reciprocable member is also rotatable and is provided with follower means for engagement with said lever means to selectively cause said lever means to rotate in a direction to cause the means connected to said lever means and arranged in operative engagement with said adjustable member to rotate the latter into a certain third position.

12. In combination in an adjustable stop arrangement for fuel pumps: an adjustable member, hydraulic control means for rotatively adjusting said adjustable memher, a casing housing said hydraulic control means, lever means tiltably mounted in said casing and operatively connected to said hydraulic control means to be tilted by the latter, said lever means being tiltable in a first direction and a second direction opposite to said first direction, means connected to said lever means and arranged in operative engagement with said adjustable member to rotate the latter in a first sense in response to a movement of said lever means in said first direction and to rotate said plunger in a second sense opposite to said first sense in response to a movement of said lever means in said second direction, said lever means having a first bore therein with the axis thereof perpendicular to the tilting direction of said lever means and also being provided with a second bore transverse to said first bore and leading into said first bore, a bendable resilient abutresilient abutment element, means reciprocably mounted in said casing and operable to move the free end of said resilient abutment element in front of said window to thereby make said resilient abutment element ineitective as abutment and allow said lever means to tilt toward the fixed end of said resilient abutment element, and sheet metal means partly covering said first bore at the entrance portion thereof, said sheet metal means engaging said reciprocable means mounted in said casing when the tip of the resilient abutment element has slightly entered said window.

13. In combination in an adjustable stop arrangement for fuel pumps: an adjustable member, a casing, a control member reciprocably mounted in said casing and provided with means engaging said adjustable member for selectively adjusting the same in one or the opposite direction, extension means connected to said control member, a flexible first abutment element normally having one end thereof in abutment with said extension means to thereby hold said adjustable member in a first position, spring means continuously urging said extension means to move in a direction toward the other end of said abutment element, a second abutment element spaced from said one end of said first abutment element in axial direction thereof and in a direction toward the other end of said first abutment element, said extension means being provided with a window near the normal point of contact of said one end of said first abutment element with said extension means, and manually operable deflecting means operable to deflect said one end of said first abutment element to bring said one end into alignment with said window thereby causing said spring means to move said extension means into contact with said second abutment element and causing said control member connected to said extension means to move said adjustable member into a second position.

14. An arrangement according to claim 13 in which the flexible abutment member has connected thereto a threaded portion threadedly and adjustably engaging a threaded bore in said casing for fine adjustment of said first abutment element.

References Cited in the file of this patent UNITED STATES PATENTS 2,509,358 Krieg May 30, 1950 2,716,901 Howe Sept. 6, 1955 2,729,168 Ziesche Ian. 3, 1956

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