Marine reduction and reverse gear unit
A marine reduction and reverse gear unit having an output shaft disposed at an acute (or obtuse) angle with respect to an input shaft 7 comprises: a drive gear 15 for transmitting torque from the input shaft 7 ; first and second driven gears 30, 31 engaged with the drive gear and disposed on the right and left sides thereof to sandwich the drive gear between the first and second driven gears; a reverse gear 16 connected to the drive gear 15 via a reverse hydraulic clutch 16 ; a first forward speed gear 33 connected to the first driven gear 30 via a hydraulic clutch; a second forward speed gear connected to the second driven gear 31 via a hydraulic clutch; and an output gear 26 fixed on the output shaft and engaged directly with one of the reverse gear 16 , first forward speed gear 33 and second forward speed gear 36 , or engaged therewith via idle gears to thereby receive the transmitted torque. This marine reduction and reverse gear unit provides a stable boat speed and enhanced acceleration performance by increasing the number of engine revolutions when wakeboarding.
1. A marine reduction and reverse gear unit having an output shaft disposed at an acute or obtuse angle with respect to an input shaft, the gear unit comprising:
a drive gear for transmitting torque from the input shaft;
first and second driven gears engaged with the drive gear and disposed on the right and left sides of the drive gear to sandwich the drive gear therebetween;
a reverse gear connected to the drive gear via a reverse hydraulic clutch;
a first forward speed gear of a first speed reduction ratio connected to the first driven gear via a first forward speed hydraulic clutch;
a second forward speed gear of a second speed reduction ratio connected to the second driven gear via a second forward speed hydraulic clutch; and
an output gear fixed on the output shaft and engaged directly with any one of said reverse gear, first forward speed gear and second forward speed gear or engaged therewith via idle gears to thereby receive the transmitted torque.
2. A marine reduction and reverse gear unit according to claim 1 wherein the drive gear is fixed on the input shaft, and the reverse gear is rotatably supported by the input shaft; the first driven gear and the first forward speed gear are supported by a first support shaft; and the second driven gear and the second forward speed gear are supported by a second support shaft.
3. A marine reduction and reverse gear unit according to claim 1 wherein the input shaft has a bevel gear fixed thereon; the drive gear or a gear for transmitting rotation to the drive gear is engaged with the bevel gear to transmit torque from the input shaft to the drive gear; the drive gear and the reverse gear are supported by a third shaft; the first driven gear and the first forward speed gear are supported by a first support shaft; and the second driven gear and the second forward speed gear are supported by a second support shaft.
4. A marine reduction and reverse gear unit according to claim 1 further comprising a hydraulic circuit for controlling hydraulic pressure of the reverse hydraulic clutch, first forward speed hydraulic clutch, and second forward speed hydraulic clutch,
the hydraulic circuit comprising a shift control valve for switching oil passages to supply hydraulic oil to the first forward speed hydraulic clutch or to the second forward speed hydraulic clutch,
the shift control valve being a pilot-operated spring-return directional control valve using the primary hydraulic pressure as pilot pressure and configured to switch from an oil passage for supplying hydraulic oil to the second forward speed hydraulic clutch to an oil passage for supplying hydraulic oil to the first forward speed hydraulic clutch, based on the increase of hydraulic pressure.
5. A marine reduction and reverse gear unit according to claim 4 wherein the shift control valve is a 3-position directional control valve configured in such a manner that when the valve is in the center position, hydraulic oil is supplied to both of the oil passages for supplying hydraulic oil to the first forward speed hydraulic clutch and the second forward speed hydraulic clutch.
6. A marine reduction and reverse gear unit according to claim 4 wherein the pilot oil passage of the shift control valve is provided with a variable throttle or a variable flow-control valve.
7. A marine reduction and reverse gear unit according to claim 4 wherein the return spring of the shift control valve is provided with a spring force adjustment mechanism.