| 摘要 |
A dental handpiece which has a drive transmission for transmitting the rotation from a motor to a socket receiving a tool for rotation in the head of the handpiece and having at least one cooling agent line formed in sections with two of the sections being connected to one another by a rotatable connection characterized by a first drive shaft having a direct coupling with the drive shaft of the drive part at one end and having two coaxially arranged gears of different number of teeth disposed on the other end, a first sleeve supporting the first drive shaft and having each cooling line section terminating in an annular groove forming part of the rotatable connection, a second sleeve telescopically received on the first sleeve and having each cooling line section starting with a radially extending port for communicating with an annular groove, a first releasable connection between the first sleeve and the housing of the drive part which does not allow any rotation therebetween, a second releasable connection between the first sleeve and second allowing rotational movement without axial displacement, a grip part formed by the first, second sleeves and an outer sleeve covering which receives a neck portion of the head part and supports a second drive shaft having a gear at each end and mountable so that either the gear at one end is engaged with one of the two gears of the first drive shaft or the gear at the opposite end is engaged with the other of the two gears to enable a different gear ratio between the first and second drive shafts.
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