Hydraulic device with decoupled filler insert for hydraulic circuit volume reduction

A hydraulic transmission for a work vehicle, the hydraulic transmission comprising:

• a plurality of gears providing multiple gear ratios;
• a clutch for shifting the plurality of gears among the multiple gear ratios, the clutch powered at least in part by hydraulic pressure;
• a gearbox body mounting the plurality of gears and the clutch within an internal cavity, the gearbox body having a first surface, a second surface and wall structure between the first surface and the second surface, the wall structure defining a plurality of internal passages including an access passage and a hydraulic fluid passage, the access passage at least in part having a cylindrical inner wall surface of a first diameter, the access passage extending through the wall structure from an access opening in the gearbox body to the hydraulic fluid passage, the hydraulic fluid passage extending through the wall structure from an entry opening in the first surface of the gearbox body to an exit opening in the second surface of the gearbox body to deliver hydraulic fluid through the wall structure from the entry opening to the exit opening;
• one or more control valves in fluid communication with the hydraulic fluid passage and configured to activate the clutch;
• a plug fixedly or removably mounted to the gearbox body to close the access opening;
• and
• a filler insert disposed proximate or coupled to the plug within the access passage, the filler insert having a cylindrical shank at least in part having a circular cross-section of a second diameter that is less than the first diameter of the inner wall surface of the access passage so as to be decoupled from the inner wall surface of the access passage;
• wherein an annular space between the shank of the filler insert and the inner wall surface of the access passage allows the hydraulic fluid to encircle at least a part of the shank of the filler insert.

A work vehicle comprising:

• a hydraulic transmission including:
• a plurality of gears providing multiple gear ratios;
• a clutch for shifting the plurality of gears among the multiple gear ratios, the clutch powered at least in part by hydraulic pressure;
• a gearbox body mounting the plurality of gears and the clutch within an internal cavity, the gearbox body having a first surface, a second surface and wall structure between the first surface and the second surface, the wall structure defining a plurality of internal passages including an access passage and a hydraulic fluid passage, the access passage at least in part having a cylindrical inner wall surface of a first diameter, the access passage extending through the wall structure from an access opening in the gearbox body to the hydraulic fluid passage, the hydraulic fluid passage extending through the wall structure from an entry opening in the first surface of the gearbox body to an exit opening in the second surface of the gearbox body to deliver hydraulic fluid through the wall structure from the entry opening to the exit opening;
• one or more control valves in fluid communication with the hydraulic fluid passage and configured to activate the clutch;
• a plug fixedly or removably mounted to the gearbox body to close the access opening;
• and
• a filler insert disposed proximate or coupled to the plug within the access passage, the filler insert having a cylindrical shank at least in part having a circular cross-section of a second diameter that is less than the first diameter of the inner wall surface of the access passage so as to be decoupled from the inner wall surface of the access passage;
• wherein an annular space between the shank of the filler insert and the inner wall surface of the access passage allows the hydraulic fluid to encircle at least a part of the shank of the filler insert.