Rocker arm

1. A rocker arm for transmitting rotational motion from a camshaft to opening and closing motion of a combustion valve in an internal combustion engine, said rocker arm comprising:

an outer arm with an outer follower comprising a first outer roller and a second outer roller both supported on an outer arm roller shaft which is centered about, and extends along, an outer arm roller shaft axis about which said first outer roller and said second outer roller rotate, said outer arm roller shaft having 1) an outer arm roller shaft first portion having a first diameter which is supported in said outer arm by a first outer bearing; 2) an outer arm roller shaft second portion having a second diameter which is supported in said outer arm by a second outer bearing; and 3) an outer arm roller shaft third portion having a third diameter such that said third diameter is smaller than said first diameter and is also smaller than said second diameter;

an inner arm which selectively pivots relative to said outer arm, said inner arm having an inner follower and also having an inner arm aperture through which said outer arm roller shaft extends such that said outer arm roller shaft third portion is located within said inner arm aperture;

a lost motion spring which biases said inner arm to pivot relative to said outer arm in a first direction; and

a lock pin which moves between 1) a coupled position in which said lock pin prevents said inner arm from pivoting relative to said outer arm past a predetermined position of said inner arm relative to said outer arm in a second direction which is opposite of said first direction and 2) a decoupled position in which said lock pin permits said inner arm to pivot relative to said outer arm past said predetermined position in said second direction.

2. A rocker arm as in claim 1 , wherein said inner follower comprises an inner roller which is supported on an inner arm roller shaft which is centered about, and extends along an inner arm roller shaft axis about which said inner roller rotates, said inner roller being supported on said inner arm roller shaft by an inner bearing located radially between said inner roller and said inner arm roller shaft, said inner arm roller shaft having an inner arm roller shaft aperture extending therethrough within which said outer arm roller shaft third portion is located.

3. A rocker arm as in claim 2 , wherein said outer arm roller shaft first portion and said outer arm roller shaft second portion are not disposed within said inner arm roller shaft aperture.

4. A rocker arm as in claim 1 , wherein said outer arm roller shaft first portion and said outer arm roller shaft second portion are not disposed within said inner arm aperture.

5. A rocker arm as in claim 1 , wherein said outer arm roller shaft third portion is located axially between said outer arm roller shaft first portion and said outer arm roller shaft second portion.

6. A rocker arm as in claim 1 , wherein said outer arm roller shaft third portion connects said outer arm roller shaft first portion to said outer arm roller shaft second portion.

7. A rocker arm for transmitting rotational motion from a camshaft to opening and closing motion of a combustion valve in an internal combustion engine, said rocker arm comprising:

an outer arm with an outer follower comprising a first outer roller and a second outer roller both supported on an outer arm roller shaft which is centered about, and extends along, an outer arm roller shaft axis about which said first outer roller and said second outer roller rotate, said outer arm roller shaft having 1) an outer arm roller shaft first portion having a first diameter which is supported in said outer arm; 2) an outer arm roller shaft second portion having a second diameter which is supported in said outer arm; and 3) an outer arm roller shaft third portion having a third diameter such that said third diameter is smaller than said first diameter and is also smaller than said second diameter;

an inner arm which selectively moves relative to said outer arm, said inner arm having an inner arm aperture through which said outer arm roller shaft extends such that said outer arm roller shaft third portion is located within said inner arm aperture;

a lost motion spring which biases said inner arm to move relative to said outer arm in a first direction; and

a lock pin which moves between 1) a coupled position in which said lock pin prevents said inner arm from moving relative to said outer arm past a predetermined position of said inner arm relative to said outer arm in a second direction which is opposite of said first direction and 2) a decoupled position in which said lock pin permits said inner arm to move relative to said outer arm past said predetermined position in said second direction.

8. A rocker arm as in claim 7 , wherein said inner arm includes an inner follower which comprises an inner roller which is supported on an inner arm roller shaft which is centered about, and extends along an inner arm roller shaft axis about which said inner roller rotates, said inner arm roller shaft having an inner arm roller shaft aperture extending therethrough within which said outer arm roller shaft third portion is located.

9. A rocker arm as in claim 8 , wherein said outer arm roller shaft first portion and said outer arm roller shaft second portion are not disposed within said inner arm roller shaft aperture.

10. A rocker arm as in claim 7 , wherein said outer arm roller shaft first portion and said outer arm roller shaft second portion are not disposed within said inner arm aperture.

11. A rocker arm as in claim 7 , wherein said outer arm roller shaft third portion is located axially between said outer arm roller shaft first portion and said outer arm roller shaft second portion.

12. A rocker arm as in claim 7 , wherein said outer arm roller shaft third portion connects said outer arm roller shaft first portion to said outer arm roller shaft second portion.