CAM CLUTCH

A-1. DUAL DRIVE AND TWO-SPEED DRIVE
Dual drive is a drive system in which two sets of
driving units are installed instead of one driven unit,
and the driven unit is driven by one or both of them as
required. With dual drive, a drive system which has
two sets of driving units having different speeds of
rotation is referred to as “two-speed drive”, and the
driven unit is driven at either high or low speed.
Normally, each driving unit uses one Cam Clutch
which works as an automatic switcher for the driving
units. In the figure on the right, when the driven unit is
to be driven by driving unit A in the direction of the
arrow, Cam Clutch A engages to transmit the rotating
power of the outer race to the inner race i.e., to the
driven unit, and drives it at a preset speed of rotation.
At this point, since the inner race of Cam Clutch B
which is connected to the driven unit also rotates in
the direction of the arrow, Cam Clutch B does not
engage but overruns, thus disconnecting the driving
unit B from the driven unit. Conversely, when the
driven unit is to be driven by driving unit B in the
direction of the arrow, Cam Clutch B engages to
transmit the rotating power of the outer race to the
inner race, i.e., to the driven unit, and drives it at a
preset speed of rotation. At this time, Cam Clutch A
overruns to disconnect driving unit A. Cam Clutch
applications are divided into four types (as indicated
in the table on the right) depending on the
overrunning speed and the engaging speed.
Application
High-speed overrunning
and high-speed
engagement.
High-speed overrunning
and medium and
low-speed engagement.
High-speed overrunning
and low-speed
engagement.
Medium and low-speed
overrunning and
medium and low-speed
engagement.
Overrunning
speed
700 r/min
and up
700 r/min
and up
700 r/min
and up
Up to
700 r/min
Engaging
speed
700 r/min
and up
Up to
700 r/min
Up to
200 r/min
Up to
700 r/min
Applicable
series
Cam Clutch
Box, MZ,
MZEU
Cam Clutch
Box, MZ,
MZEU
Cam Clutch
Box, MZ,
MZEU, MR,
BR, BREU, TB
MZ, MG,
200, MZEU,
PB, LD
Page
73 to 75,
22 to 31
73 to 75,
22 to 31
73 to 75,
22 to 31,
56 to 68,
76
22 to 31,
37, 69
A-1-1. High-Speed Overrunning and High-Speed Engagement
(Overrunning speed = 700 r/min and up)
(Engaging speed = 700 r/min and up)
Example of fan or pump drive
This example shows a high-speed system in which a
driven unit (pump or fan) is driven by a dual drive
system consisting of a motor and a turbine. The Cam
Clutches are used for automatic switching between
the driving units. The fan is normally driven by the
Cam Clutch on the turbine side. When starting, or
when steam pressure to the turbine drops, the motor
takes over from the turbine to drive the fan. Cam
Clutch A engages when the turbine drives the fan, and
it overruns when the motor drives the fan. Conversely,
Cam Clutch B overruns when the turbine drives the
fan, and it engages when the motor drives the fan.
The driving devices can be changed over without
switching the clutch. This is because the difference in
the speed of rotation between the motor and turbine
turns the Cam Clutches on and off, and the driving
device rotating the fastest is connected automatically
to the driven unit. Overrunning and engagement of the
Cam Clutches are performed continuously at speeds
faster than 700 r/min.
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