Combination relief vent and dipstick apparatus for an oil filled pin joint

An oil filled pin joint, comprising:

• a structural element defining a sealed cavity containing at least one bearing supporting a pin for rotation relative thereto and a quantity of oil for lubricating the at least one bearing and the pin, the structural element including an orifice above the oil communicating with the cavity;
• and
• a combination relief vent and dipstick apparatus removably mounted in the orifice, including a body member having first and second opposite end portions, a passage extending therethrough between the opposite end portions, a first valve seat extending around the passage, structure for removably mounting the body member in the orifice with the first end portion in communication with the cavity, the first end portion including a dipstick adapted to extend into the cavity so as to be at least partially immersed in the oil in the cavity when at a predetermined level so as to provide an indicator of the level, a valve assembly mounted in the passage of the body member, the valve assembly including a first valve member movable between a closed position in a sealed relation to the first valve seat and a range of open positions spaced from the first valve seat, a first biasing member yieldably urging the first valve member toward the closed position, fluid in the cavity at a pressure greater than a first predetermined pressure level being operable to move the first valve member in opposition to the first biasing member away from the closed position to one of the open positions allow some of the fluid to escape from the cavity to atmosphere through the passage such that the pressure is reduced to the first predetermined pressure level, the valve assembly including a second valve seat, a second valve member movable between a closed position in sealed relation to the second valve seat and a range of open positions spaced from the second valve seat, and a second biasing member yieldably urging the second valve member toward its closed position, fluid in the cavity at a pressure below a second predetermined pressure level being operable to move the second valve member in opposition to the second biasing member away from its closed position to allow fluid from atmosphere to enter the cavity through the passage to allow the pressure in the cavity to rise to the second predetermined pressure level.

A combination relief vent and dipstick apparatus adapted to be removably mounted in an orifice of a pin joint in communication with a sealed cavity therein adapted for containing a predetermined level of oil, the apparatus comprising:

• a body member having first and second opposite end portions, a passage extending therethrough between the opposite end portions, a valve seat extending around the passage, and structure for removably mounting the body member in the orifice with the first end portion in communication with the cavity, the first end portion including a dipstick adapted to extend into the cavity so as to be partially immersed in the oil in the cavity when at the predetermined level so as to provide an indicator of the level;
• and
• a valve assembly removably mounted in the passage of the body member, the valve assembly including a body having a passage therethrough and a valve seat extending around the passage, a valve member movable between a closed position in sealed relation to the valve seat and a range of open positions spaced from the valve seat, and a biasing member yieldably urging the valve member toward the closed position, fluid in the cavity at a pressure greater than a predetermined pressure level being operable to move the valve member in opposition to the biasing member away from the closed position to allow some of the fluid to escape from the cavity to atmosphere through the passage such that the pressure is reduced to the predetermined pressure level, and fluid in the cavity at a pressure less than a predetermined pressure level being operable to move the valve member in opposition to the biasing member away from the closed position to allow some external fluid to enter the cavity from the atmosphere through the passage such that the pressure rises to the predetermined pressure level.