  For the past couple of decades, the Parkes radio telescope has been regularly
observing the millisecond pulsars in 47 Tucanae (47 Tuc). This long-term timing
program was designed to address a wide range of scientific issues related to
these pulsars and the globular cluster where they are located. In this paper,
the first of a series, we address one of these objectives: the characterization
of four previously known binary pulsars for which no precise orbital parameters
were known, namely 47 Tuc P, V, W and X (pulsars 47 Tuc R and Y are discussed
elsewhere). We determined the previously unknown orbital parameters of 47 Tuc V
and X and greatly improved those of 47 Tuc P and W. For pulsars W and X we
obtained, for the first time, full coherent timing solutions across the whole
data span, which allowed a much more detailed characterization of these
systems. 47 Tuc W, a well-known tight eclipsing binary pulsar, exhibits a large
orbital period variability, as expected for a system of its class. 47 Tuc X
turns out to be in a wide, extremely circular, 10.9-day long binary orbit and
its position is ~3.8 arcmin away from the cluster center, more than three times
the distance of any other pulsar in 47 Tuc. These characteristics make 47 Tuc X
a very different object with respect to the other pulsars of the cluster.
