Blade rotation system

1. A blade rotation system, comprising:

an hydraulic gear motor having a drive shaft, the drive shaft being configured with one or more first permanent magnets coupled thereto;

wherein the hydraulic gear motor includes a gear system, and an inlet port and outlet port in fluid communication with the gear system and through which pressurized hydraulic fluid is passed to drive the hydraulic gear motor;

a spindle shaft adapted for connection to a blade, the spindle shaft being configured with one or more second permanent magnets coupled thereto;

wherein the one or more first permanent magnets are configured to magnetically engage the one or more second permanent magnets so that rotation of the drive shaft by the hydraulic gear motor translates into rotation of the spindle shaft to impart motion to the blade;

wherein the hydraulic gear motor is configured such that as the pressurized hydraulic fluid passes from the inlet port to the outlet port, the hydraulic fluid drives the gear system to rotate the drive shaft and thus the spindle shaft to which the drive shaft is magnetically engaged; and

a cup shape chamber, wherein the one or more first permanent magnets project axially into an open end of the cup shape chamber;

wherein the cup shape chamber includes a flow passage for receiving a cooling fluid to cool the cup shape chamber.

2. The blade rotation system of claim 1 , wherein the one or more first permanent magnets are radially spaced from the one or more second permanent magnets.

3. The blade rotation system of claim 1 , wherein the one or more first permanent magnets are coupled to the drive shaft by a drive rotor, and the one or more second permanent magnets are coupled to the spindle shaft by a driven rotor, such that the drive rotor magnetically drives the driven rotor.

4. The blade rotation system of claim 3 , wherein the one or more first permanent magnets are mounted to an outer periphery of the drive rotor, and the one or more second permanent magnets are mounted to an inner periphery of the driven rotor.

5. The blade rotation system of claim 4 , wherein the one or more first permanent magnets are arranged in a first circular shape and the one or more second permanent magnets are arranged in a second circular shape, and the second circular shape is radially outward of the first circular shape.

6. The blade rotation system of claim 1 , wherein the cup shape chamber has an axially protruding tubular portion with the open end at one axial end of the tubular portion and a wall at an opposite axial end of the tubular portion, wherein the peripheral edge of the open end is fixed relative to an end wall of the hydraulic gear motor to seal the one or more first permanent magnets from the driven rotor and the one or more second permanent magnets.

7. The blade rotation system of claim 1 , wherein the flow passage is in fluid communication with an open space surrounding a portion of the drive shaft and the cooling fluid comes from a gear housing of the hydraulic gear motor.

8. The blade rotation system of claim 1 , wherein the inlet port and outlet port are the only hydraulic fluid passages in the hydraulic gear motor.

9. The blade rotation system of claim 1 , wherein the drive shaft of the hydraulic gear motor does not have a shaft seal.

10. The blade rotation system of claim 1 , wherein the hydraulic gear motor does not have a case drain.

11. The blade rotation system of claim 1 , wherein the one or more first permanent magnets are configured to disengage from the one or more second permanent magnets when a maximum rated torque is achieved.