Marine drive with dual propeller exhaust and lubrication

A marine drive comprising:

• a housing having a horizontal bore and an intersecting vertical bore therein;
• a vertical drive shaft positioned in said vertical bore;
• a spool positioned in said horizontal bore;
• an inner propeller shaft, and a hollow outer propeller shaft positioned concentrically over said inner propeller shaft to form a dual propeller shaft assembly, said dual propeller shaft assembly positioned in said spool, said inner and outer propeller shafts rotating in opposite rotational directions along a common axis;
• a forward propeller mounted to said outer propeller shaft;
• an aft propeller mounted to said inner propeller shaft, one of said propellers being a right hand rotation propeller, the other of said propellers being a left hand rotation propeller;
• an exhaust passage comprising a first passage in said housing communicating with said horizontal bore at said spool;
• an oil passage comprising a second passage in said housing communicating with said horizontal bore forwardly of said first passage and rearwardly of said vertical bore and lubricating said dual propeller shaft assembly.

A marine drive comprising:

• a housing having a horizontal bore and an intersecting vertical bore therein;
• a spool positioned in said horizontal bore;
• an inner propeller shaft, and a hollow outer propeller shaft positioned concentrically over said inner propeller shaft to form a dual propeller shaft assembly, said dual propeller shaft assembly positioned in said spool, said inner and outer propeller shafts rotating in opposite rotational directions along a common axis;
• a forward propeller mounted to said outer propeller shaft;
• an aft propeller mounted to said inner propeller shaft, one of said propellers being a right hand rotation propeller, the other of said propellers being a left hand rotation propeller;
• an exhaust passage comprising a first passage in said housing communicating with said horizontal bore at said spool;
• an oil passage comprising a second passage in said housing communicating with said horizontal bore forwardly of said first passage and lubricating said dual propeller shaft assembly,
• wherein said spool is thread mounted within said horizontal bore at a first set of threads, and comprising:
• a vertical driveshaft positioned in said vertical bore;
• a pinion driving gear mounted on the lower end of said vertical driveshaft;
• a first driven gear on said inner propeller shaft and engaged by said pinion gear and drivingly rotating said inner propeller shaft in a first rotational direction;
• a second driven gear on said outer propeller shaft and engaged by said pinion gear and drivingly rotating said outer propeller shaft in a second rotational direction;
• a tapered roller thrust bearing supporting said second driven gear for rotation in said housing, said tapered roller thrust bearing having
• an inner race engaging said second driven gear, and
• an outer race engaging said housing in said horizontal bore;
• a threaded locking ring thread mounted within said horizontal bore at a second set of threads and engaging said outer race to prevent rearward movement of said second driven gear,
• wherein said first and second sets of threads are axially spaced such that said spool is spaced rearwardly of said locking ring by an axial gap therebetween, and wherein said second passage communicates with said horizontal bore at said axial gap.

A marine drive comprising:

• a housing having a horizontal bore and an intersecting vertical bore therein;
• a vertical drive shaft positioned in said vertical bore;
• a spool positioned in said horizontal bore;
• an inner propeller shaft, and a hollow outer propeller shaft positioned concentrically over said inner propeller shaft to form a dual propeller shaft assembly, said dual propeller shaft assembly positioned in said spool, said inner and outer propeller shafts rotating in opposite rotational directions along a common axis;
• an exhaust passage comprising a first passage in said housing communicating with said horizontal bore at said spool;
• said spool comprising a cylindrical member comprising:
• a first outer diameter portion engaging said housing within said horizontal bore;
• a second reduced outer diameter portion within said horizontal bore and aft of said first outer diameter portion and defining an annular recess receiving exhaust from said first housing passage;
• a third outer diameter portion aft of said second outer diameter portion and engaging said housing and having a plurality of slots extending rearwardly therethrough;
• a fourth reduced outer diameter portion aft of said third outer diameter portion and external of said horizontal bore;
• a forward propeller mounted to said outer propeller shaft;
• an aft propeller mounted to said inner propeller shaft, one of said propellers being a right hand rotation propeller, the other of said propellers being a left hand rotation propeller, each propeller having a hub with through-hub exhaust passages, such that exhaust from said annular recess flows rearwardly through said slots through said third outer diameter portion then rearwardly through said hubs;
• an oil passage comprising a second passage in said housing communicating with said horizontal bore forwardly of said first housing passage and rearwardly of said vertical bore and lubricating said dual propeller shaft assembly.

A marine drive comprising:

• a housing having a horizontal bore and an intersecting vertical bore therein;
• a spool positioned in said horizontal bore;
• an inner propeller shaft, and a hollow outer propeller shaft positioned concentrically over said inner propeller shaft to form a dual propeller shaft assembly, said dual propeller shaft assembly positioned in said spool, said inner and outer propeller shafts rotating in opposite rotational directions along a common axis;
• an exhaust passage comprising a first passage in said housing communicating with said horizontal bore at said spool;
• said spool comprising a cylindrical member comprising:
• a first outer diameter portion engaging said housing within said horizontal bore;
• a second reduced outer diameter portion within said horizontal bore and aft of said first outer diameter portion and defining an annular recess receiving exhaust from said first housing passage;
• a third outer diameter portion aft of said second outer diameter portion and engaging said housing and having a plurality of slots extending rearwardly therethrough;
• a fourth reduced outer diameter portion aft of said third outer diameter portion and external of said horizontal bore;
• a forward propeller mounted to said outer propeller shaft;
• an aft propeller mounted to said inner propeller shaft, one of said propellers being a right hand rotation propeller, the other of said propellers being a left hand rotation propeller, each propeller having a hub with through-hub exhaust passages, such that exhaust from said annular recess flows rearwardly through said slots through said third outer diameter portion then rearwardly through said hubs;
• an oil passage comprising a second passage in said housing communicating with said horizontal bore forwardly of said first housing passage and lubricating said dual propeller shaft assembly, wherein:
• said third outer diameter portion of said spool extends rearwardly externally of said horizontal bore and includes a raised annular shoulder of outer diameter greater than the inner diameter of said horizontal bore and engaging said housing at the aft end of said horizontal bore, said third outer diameter portion having an aft end defining an annulus facing axially rearwardly toward the hub of said forward propeller;
• said fourth outer diameter portion extends rearwardly within said hub of said forward propeller, such that exhaust through said hub of said forward propeller is concentric around said fourth outer diameter portion of said spool;
• said spool is thread mounted within said horizontal bore at a first set of threads;
• and comprising:
• a vertical drive shaft positioned in said vertical bore;
• a pinion driving gear mounted on the lower end of said vertical driveshaft;
• a first driven gear on said inner propeller shaft and engaged by said pinion gear and drivingly rotating said inner propeller shaft in a first rotational direction;
• a second driven gear on said outer propeller shaft and engaged by said pinion gear and drivingly rotating said outer propeller shaft in a second rotational direction;
• a tapered roller thrust bearing supporting said second driven gear for rotation in said housing, said tapered roller thrust bearing having an inner race engaging said second driven gear, and an outer race engaging said housing in said horizontal bore;
• a threaded locking ring thread mounted within said horizontal bore at a second set of threads and engaging said outer race to prevent rearward movement of said second driven gear;
• said first and second sets of threads being axially spaced such hat said spool is spaced rearwardly of said locking ring by an axial gap therebetween, said second housing passage communicating with said horizontal bore at said axial gap;
• a first aft bearing in a first annulus between said outer propeller shaft and said spool at said fourth outer diameter portion and supporting said outer propeller shaft for rotation with said spool;
• a second aft bearing in a second annulus between said inner and outer propeller shafts aft of said first aft bearing and supporting said inner propeller shaft for rotation within said outer propeller shaft;
• wherein said oil passage supplies oil to said first annulus to lubricate said first aft bearing, and said outer propeller shaft has a passage therethrough supplying oil from said first annulus to said second annulus to lubricate said second aft bearing.