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AssigneeBrunswick Corporation
InventorsJohn M. Griffiths, David A. Gussert, Michael A. Karls
Estimating the term…
A marine drive has a reverse thrust cup on the propeller shaft between the propeller hub and the rear retaining nut. The reverse thrust cup permits the propeller hub to slide on the propeller shaft fore and aft. When the marine drive is in the forward direction the rearward thrust of the propeller forces the propeller hub to the forward position thereby directing engine exhaust out the rear of the propeller hub. Conversely, when the marine drive is in the reverse direction, the forward thrust created by the propeller hub forces the propeller hub to the rearward position thereby directing exhaust out a forward exhaust opening forward of the propeller blades increasing the reverse thrust of the marine drive.
A method of retrofitting a reversible marine drive to increase reverse thrust, the marine drive having a lower gearcase, a gearcase exhaust passage, a propeller shaft extending rearwardly from the gearcase and having a threaded rear end, a propeller hub drivingly mounted to the propeller shaft and having a first inner diameter portion in contact with the propeller shaft and a second inner diameter portion radially outward of the first inner diameter portion and a first outer diameter portion between the first and second inner diameter portions wherein the first outer diameter portion and the second inner diameter portion define a through-hub exhaust passage communicating with the gearcase exhaust passage and a rear underwater exhaust discharge opening being generally rearward in the propeller hub, a retaining nut threadedly engaging the threaded rear end of the propeller shaft, and a rear thrust washer disposed between the propeller hub and the retaining nut such that the propeller hub has limited fore and aft movement with respect to the propeller shaft, the method comprising replacing the rear thrust washer with a reverse thrust cup, the reverse thrust cup having at least first and second diameter portions, the first diameter portion being forward of the second diameter portion and having a diameter less than that of the first inner diameter portion of the propeller hub, and the second diameter portion being rearward of the second inner diameter portion of the propeller hub and having a diameter greater than that of the second inner diameter portion of the propeller hub, and wherein the propeller hub is allowed to slide on the propeller shaft from a forward position allowing exhaust to discharge out the rear underwater exhaust discharge opening to a rearward position allowing exhaust to discharge out a forward underwater exhaust discharge opening.
A marine drive having a reversible propeller to selectively drive a boat in the forward and reverse directions and having increased reverse thrust in the reverse direction, comprising:
A retrofit kit for increasing reverse thrust in a marine drive having a lower gearcase, a gearcase exhaust passage, a propeller shaft extending rearwardly from the gearcase and having a threaded rear end, a propeller hub drivingly mounted to the propeller shaft and having a first inner diameter portion in contact with the propeller shaft and a second inner diameter portion radially outward of the first inner diameter portion and a first outer diameter portion between the first and second inner diameter portions wherein the first outer diameter portion and the second inner diameter portion define a through-hub exhaust passage communicating with the gearcase exhaust passage and a rear underwater exhaust discharge opening which is generally rearward in the propeller hub, a retaining nut threadedly engaging the threaded rear end of the propeller shaft, and a rear thrust washer disposed between the propeller hub and the retaining nut, the retrofit kit comprising a reverse thrust cup replacing the rear thrust washer disposed between the propeller hub and the retaining nut on the propeller shaft, the reverse thrust cup having at least first and second diameter portions, the first diameter portion being forward of the second diameter portion and having a diameter less than that of the first inner diameter portion of the propeller hub, and the second diameter portion being rearward of the second inner diameter portion of the propeller hub and having an increasing diameter rearward wherein a rearward portion of the reverse thrust cup has a diameter greater than that of the second inner diameter portion of the propeller hub.
Dependencies are inferred from the claim text.