Piston and cylinder assembly with an indicator pin device

1. A piston and cylinder assembly comprising:

a cylinder housing;

a piston and rod assembly slidably mounted in said cylinder housing and having a piston rod extending through one end of said cylinder housing;

a second end of said cylinder housing having an indicator pin normally resiliently biased to an extended position where the indicator pin has a distal section that extends outwardly from an exterior surface of said cylinder housing to be exposed and visible from an exterior of said piston and cylinder assembly;

a spring element engaged with said indicator pin for resiliently biasing said indicator pin to an extended position;

said indicator pin operably connected with a retracting device mounted within said cylinder housing; and

said retracting device being engagable with said piston and rod assembly to retract said indicator pin against the bias of said spring element from its extended position to a retracted position when said piston and rod assembly is at an end of its return stroke.

2. A piston and cylinder assembly as defined in claim 1 further comprising:

said piston and rod assembly dividing said cylinder housing into varying sized first and second pressure chambers with said first pressure chamber surrounding said piston rod from said piston to said one end of said cylinder housing and said second pressure chamber extending from an opposite side of said piston to a second end of said cylinder housing;

said piston and rod assembly having an extension extending into said second pressure chamber;

one of said piston rod and said extension having a recess between axially spaced walls;

a locking pin mounted to said cylinder housing for extending into one of said pressure chambers and movable between a radially inner position where it engages said recess in an axially fixed position and mechanically locks said piston and rod assembly against axial motion and a radially outer position where it disengages and allows said piston and rod assembly to axially move; and

said locking pin being spring biased to said radially inner position and responsive to pressure above a predetermined amount in one of said pressure chambers when in said radially inner position to move radially outward against said spring bias.

3. A piston and cylinder assembly comprising:

a cylinder housing;

a piston and rod assembly slidably mounted in said cylinder housing and having a piston rod extending through one end of said cylinder housing;

a second end of said cylinder housing having an indicator pin normally resiliently biased to an extended position where the indicator pin has a distal section that extends outwardly from an exterior surface of said cylinder housing;

said indicator pin operably connected with a retracting device mounted within said cylinder housing;

said retracting device being engagable with said piston and rod assembly to retract said indicator pin from its extended position to a retracted position when said piston and rod assembly is at an end of its return stroke; and

one of said retracting device and said piston and rod assembly having a canted surface engagable with the other of said retracting device and said piston and rod assembly to retract said piston rod radially inwardly against its normally resilient bias toward a radially extended position when said piston and rod assembly is moved to the end of its return stroke.

4. A piston and cylinder assembly as defined in claim 3 further comprising:

said indicator pin connected to a central ring section with aperture therethrough; and

said piston and rod assembly having a tapered interior end aligned to abut an inner periphery of said ring at an edge of said aperture to retract said indicator pin from its radially extended position to its radially retracted position when said piston and rod assembly is moved to the end of the return stroke.

5. A piston and cylinder assembly as defined in claim 4 further comprising:

a plunger rod and spring seat extending from said central ring section in an opposite direction from said distal section of the indictor pin from said central ring and extending in a bore of a cage; and

a spring member housed in said bore of said cage and resiliently biases the indicator pin toward the extended position against the retracting motion caused by said tapered interior end of said piston and rod assembly.

6. A piston and cylinder assembly as defined in claim 5 further comprising:

said cylinder housing having a cylindrical side wall section and an end cap member; and

said end cap member mounting said indicator pin and said retracting device and said spring member.

7. A piston and cylinder assembly as defined in claim 6 further comprising:

said indicator pin protruding out of a cylindrical side of said end cap.

8. A piston and cylinder assembly as defined in claim 7 further comprising:

said piston and rod assembly dividing said cylinder housing into varying sized first and second pressure chambers with said first pressure chamber surrounding said piston rod from said piston to said one end of said cylinder housing and said second pressure chamber extending from an opposite side of said piston to said second end;

said piston and rod assembly having an extension extending into said second pressure chamber;

said tapered interior end being a part of said extension;

said extension having a recess between axially spaced walls; and

a locking pin mounted to said cylinder housing for extending into said second pressure chamber and movable between a radially inner position where it engages said recess in said extension and mechanically locks said piston and rod assembly in said retracted position and a radially outer position where it disengages from said extension and allows said piston and rod assembly to axially move.

9. A piston and rod assembly as defined in claim 8 further comprising:

said locking pin being spring biased to said radially inner position and responsive to pressure within said second chamber above a predetermined amount to move radially outward against said spring bias.

10. A piston and cylinder assembly as defined in claim 3 further comprising:

said cylinder housing having a cylindrical side wall section and an end cap member; and

said end cap member mounting said indicator pin and said retracting device.

11. A piston and cylinder assembly comprising:

a cylinder housing;

a piston and rod assembly slidably mounted in said cylinder housing and having a piston rod extending through one end of said cylinder housing;

a second end of said cylinder housing having an indicator pin normally resiliently biased to an extended position where the indicator pin has a distal section that extends outwardly from an exterior surface of said cylinder housing;

said indicator pin operably connected with a retracting device mounted within said cylinder housing; and

said retracting device being engagable with said piston and rod assembly to retract said indicator pin from its extended position to a retracted position when said piston and rod assembly is at an end of its return stroke;

said piston and rod assembly dividing said cylinder housing into varying sized first and second pressure chambers with said first pressure chamber surrounding said piston rod from said piston to said one end of said cylinder housing and said second pressure chamber extending from an opposite side of said piston to said second end;

said piston and rod assembly having an extension extending into said second pressure chamber;

said tapered interior end being a part of said extension;

said extension having a recess between axially spaced walls; and

a locking pin mounted to said cylinder housing for extending into said second pressure chamber and movable between a radially inner position where it engages said recess in said extension and mechanically locks said piston and rod assembly in said retracted position and a radially outer position where it disengages from said extension and allows said piston and rod assembly to axially move.

12. A piston and rod assembly as defined in claim 11 further comprising:

said locking pin being spring biased to said radially inner position and responsive to pressure within said second chamber above a predetermined amount to move radially outward against said spring bias.

13. A piston and cylinder assembly comprising:

a cylinder housing;

a piston and rod assembly slidably mounted in said cylinder housing and having a piston rod extending through one end of said cylinder housing;

a second end of said cylinder housing having an indicator pin normally resiliently biased to an extended position where the indicator pin has a distal section that extends outwardly from an exterior surface of said cylinder housing;

said indicator pin operably connected with a retracting device mounted within said cylinder housing; and

said retracting device being engagable with said piston and rod assembly to retract said indicator pin from its extended position to a retracted position when said piston and rod assembly is at an end of its return stroke;

said cylinder housing having a cylindrical side wall section and an end cap member; and

said end cap member mounting said indicator pin and said retracting device.

14. A piston and cylinder assembly comprising:

a cylinder housing;

a piston and rod assembly slidably mounted in said cylinder housing and having a piston rod extending through one end of said cylinder housing;

a second end of said cylinder housing having an indicator pin normally resiliently biased to an extended position where the indicator pin has a distal section that extends outwardly from an exterior surface of said cylinder housing;

said indicator pin operably connected with a retracting device mounted within said cylinder housing; and

said retracting device being engagable with said piston and rod assembly to retract said indicator pin from its extended position to a retracted position when said piston and rod assembly is at an end of its return stroke;

said indicator pin operably connected to a lever pivotably mounted to said cylinder housing; and

said lever having a first leg section engagable by said piston and rod assembly and a section operably connected to said indicator pin.

15. A piston and cylinder assembly as defined in claim 14 further comprising:

wherein said lever is a bell crank.

16. An end cap assembly for mounting on an end of a cylinder and piston assembly, said end cap assembly comprising:

a spring element engaged to an indicator pin for resiliently biasing said indicator pin to an extended position;

said indicator pin normally biased to extend through an aperture in the end cap and protruding beyond an exterior surface of said end cap;

said indicator pin operably connected to a retracting device mounted to an interior section of said end cap assembly; and

said retracting device constructed to be operably engaged against said piston assembly to retract said indicator pin against the bias of said spring element into said aperture.

17. An end cap assembly as defined in claim 16 further comprising:

said aperture being positioned about a periphery of said end cap; and

said pin extending out of said aperture at said periphery.