(57) An intermediate drive assembly (1) is provided for a fuel pump (10) having a pump
housing (12) provided with at least one bore (20a, 20b, 20c) for receiving the intermediate
drive assembly (1) and a pumping plunger (30) which are driven, in use, in a reciprocal
manner within the bore (20a, 20b, 20c) by a drive arrangement (2) so as to pressurise
fuel within a pump chamber (32). The intermediate drive assembly (1) is arranged so
as to cooperate between the drive arrangement (2) and the pumping plunger and comprises
a tappet (34) having a base portion (38) and a side wall portion (36), and a coupling
mechanism, in use for coupling the pumping plunger (30) to the base portion (38).
The coupling mechanism comprises a spring seat (40) adapted to engage an end of the
pumping plunger (30), and interlocking means, in use for substantially preventing
relative rotation between the base portion (38) and the spring seat (40). The base
portion (38) has a drive surface (5) for cooperating with the drive arrangement (2),
a thrust surface (7) for cooperating with and imparting drive to the pumping plunger
(30), and a recess (9), the recess (9) receiving an insert (11) formed of a material
having a hardness greater than the base portion (38). The insert (11) is a clearance
fit in the recess (9).
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