[Bobcat]

For what it`s worth , Tilton told me they use a Quad seal on their Hydraulic throwout bearings and from what I could find out , McLeod uses an "O" ring . From my 30 years in the hydraulics industry ( 15 years in the hydraulic cylinder end ) , "O" rings make great static seals , but very poor dynamic seals . "0" rings tend to stick in the bore and then roll slightly when they break free and get pinched between the bore and the piston . I bet if you look at the "O" ring closely , you will see a few "nibbles" out of it . Quad seals are made to seal under movement . " O" rings are cheaper than Quad seals .... but having said that , a lot of people still use them . We never would as the field problems were just too many .