Sealed PTO damper

1. A torsion damper comprising:

a plurality of elastic elements;

a first plate drivingly engaged with the plurality of elastic elements and adapted to drivingly engage with a transmission shaft;

a gear; and

second and third plates drivingly engaged with the gear and drivingly engaged with the plurality of elastic elements, wherein at least one of the first, second, or third plates is adapted to hydraulically seal to a housing for a transmission.

2. The torsion damper of claim 1 , wherein the gear is adapted to be a power take-off gear for the transmission.

3. The torsion damper of claim 1 , wherein the gear comprises a toothed portion and a portion radially inside the toothed portion, and the portion radially inside the toothed portion is arranged to provide radial support to the elastic elements.

4. The torsion damper of claim 3 , wherein the gear comprises a connector portion radially disposed between the toothed portion and the portion radially inside the toothed portion, and the gear is fixedly connected to the second plate at the connector portion.

5. The torsion damper of claim 3 , wherein the elastic elements are arcuately-formed coil springs.

6. The torsion damper of claim 3 , further comprising a plurality of raceways disposed between the coil springs and the radially inside portion.

7. The torsion damper of claim 1 , wherein the first plate and the gear are directly drivingly engaged for a torque applied to the first plate greater than a selected damper torque.

8. The torsion damper of claim 1 , wherein the first plate or the gear includes at least one radially extending tab and the other of the first plate or the gear includes at least one window and wherein for a torque applied to the first plate greater than a selected damper torque, the first plate and the gear are directly drivingly engaged by contact between the at least one radially extending tab and the at least one window.

9. The torsion damper of claim 1 , wherein the second plate and the third plate are each hydraulically sealed to the gear and to the transmission housing.

10. The torsion damper of claim 9 , further comprising at least one o-ring, wherein at least one of the second or third plates comprises a circumferential notch for accepting the o-ring, and the plate is sealed to the gear by the o-ring.

11. The torsion damper of claim 1 , wherein the second plate radially locates the gear.

12. The torsion damper of claim 11 , wherein the second plate is adapted to be radially located by a bearing in the transmission.

13. A torsion damper comprising:

a plurality of elastic elements;

a first plate engaged with the plurality of elastic elements, with a first radial wall and a first cylindrical protrusion, the first protrusion adapted to be radially located by a first transmission bearing;

a second plate engaged with the plurality of elastic elements, with a second radial wall and a second cylindrical protrusion, the second protrusion adapted to be radially located by a second transmission bearing; and

a gear fixedly connected to and hydraulically sealed to the first and second plates, wherein the plurality of elastic elements and the first and second transmission bearings are at least partially aligned in a direction parallel to an axis of rotation for the torsion damper.

14. A torsion damper comprising:

a plurality of elastic elements;

a first plate drivingly engaged with the plurality of elastic elements and adapted to drivingly engage with a transmission shaft;

a gear;

second and third plates drivingly engaged with the gear and the plurality of elastic elements; and,

an annular space at least partially formed by the first and second plates, wherein the annular space is adapted to form a sealed channel with the transmission shaft; and wherein a portion of the gear is disposed between the second and third plates in a direction parallel to an axis of rotation for the torsion damper.