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www.shortlineparts.com/old-st...
This video shows how to install a hose as well as a coupler in the rear remotes on a John Deere 4020 tractor. The first thing to make sure of is that the inner collars of the rear remote are flush with the housing of the rear remote. If the collars are pushed in, then when you try to install the coupler, it won't snap in. To get the collars flush with the housing, grasp the oil switch and pull it towards you. This will also pull the inner collars of the rear remote out. Once they are pulled out, to install either the remote adapter or the tip of an implement or front end loader hydraulic hose, place the tip of the male coupler in the female part of the rear remote and press in until you feel it click into place. Then move the oil handle on the bottom of the remote so that it's facing to the side. This turns the oil on. To remove the coupler or the implement hose, turn the oil off by moving the oil lever so it's pointing straight towards you. A firm tug will pop the coupler out of the rear remote. Even if you forget to turn the oil off, that is okay because a safety feature automatically moves the oil lever to the OFF position whenever the coupler pops out. This is so in case the hose gets caught on something and it pulls out of the rear remote, the oil will automatically shut off and not spray all over the place.