A roller mechanism for vehicles with sliding doors, the roller mechanism comprising a body bracket which provides connection with the sliding door by means of the connection holes existing in the structure thereof and which provides carrying of the sliding door; and a sandwich bracket connected to said body bracket; said roller mechanism provides driving of the sliding door thanks to the carrier roller and the guide roller connected to said sandwich bracket by means of pins, wherein said roller mechanism further comprises: - to enable adjustment in axis Z, at least one adjustment bolt connected to a threaded hole provided on said body bracket and whose outer surface has a threaded structure and whose inner surface is gapped and having a bolt head which facilitates tightening from outside, - two bearings which provide free rotation of the adjustment bolt by means of passing through two ends of said adjustment bolt, namely the bottom and top ends thereof, - at least one contra nut connected to said adjustment bolt and which provides fixation of the adjustment made in direction Z and which contacts the body bracket when tightened, wherein - said sandwich bracket comprises a lower and an upper brackets (25, 26), and a slot hole is provided on the lower and upper brackets (25, 26), - the adjustment bolt, the bearings, and the contra nut are arranged inside the brackets (25, 26) of the sandwich bracket, - to provide rotational freedom to the sandwich bracket and to keep the other parts together the roller mechanism contains at least one axis pin, whose one end is threaded, - each bearing comprises a gap such that said axis pin passes therethrough, - - a bushing part is passed through the holes provided at the lower and upper parts of the adjustment bolt, and the bearings are passed through the bushing part fixed from the lower and upper parts and bedded, - the axis pin further passes through the adjustment bolt, threaded hole, contra nut, and the slot holes that are on the sandwich bracket, - to enable fixation of the axis pin, the rolling mechanism further comprises at least one nut which exerts pressure by contacting the upper bracket of said sandwich bracket. - to enable adjustment in axis Z, at least one adjustment bolt connected to a threaded hole provided on said body bracket and whose outer surface has a threaded structure and whose inner surface is gapped and having a bolt head which facilitates tightening from outside, - two bearings which provide free rotation of the adjustment bolt by means of passing through two ends of said adjustment bolt, namely the bottom and top ends thereof, - at least one contra nut connected to said adjustment bolt and which provides fixation of the adjustment made in direction Z and which contacts the body bracket when tightened, wherein - said sandwich bracket comprises a lower and an upper brackets (25, 26), and a slot hole is provided on the lower and upper brackets (25, 26), - the adjustment bolt, the bearings, and the contra nut are arranged inside the brackets (25, 26) of the sandwich bracket, - to provide rotational freedom to the sandwich bracket and to keep the other parts together the roller mechanism contains at least one axis pin, whose one end is threaded, - each bearing comprises a gap such that said axis pin passes therethrough, - - a bushing part is passed through the holes provided at the lower and upper parts of the adjustment bolt, and the bearings are passed through the bushing part fixed from the lower and upper parts and bedded, - the axis pin further passes through the adjustment bolt, threaded hole, contra nut, and the slot holes that are on the sandwich bracket, - to enable fixation of the axis pin, the rolling mechanism further comprises at least one nut which exerts pressure by contacting the upper bracket of said sandwich bracket.