Page 207 - Mechatronics with Experiments

MECHANISMS FOR MOTION TRANSMISSION 193
Control cylinder and piston (disc shaped)
to move clutch discs along the shaft
Input shaft

Pressurized Clutch multi discs grooved to shaft
hydraulic (Can slide along the shafts,
fluid, controlled while rotating with the shaft)
by an EH valve,
supplied by a
pump/accumulator
line
Output shaft

(a)

(b)
FIGURE 3.31: Multi disc clutch and brake concept. (a) Two-dimensional cross-sectional view
of a multi disc clutch, (b) three-dimensional cut-away view of a multi disc brake.

Multi disc clutch and brakes are perhaps the most versatile types among others. The
basic principle of torque transmission, via clutch and brakes, is the friction between two
discs. If we press two discs against each other, the friction between them will transmit
torque from one to another. Now, we extend this idea to a set of discs, where one set is
connected to shaft one, the other set connected to shaft two. In addition they are connected
to their respective shafts through axial grooves so that they can move translationally (slide
along the shaft) along the rotation axis. The two sets of discs would be placed in alternating
order in order to maximize the friction surface. The actuation mechanism for the clutch and
brakes can be mechanical, air pressure, hydraulic, electro-hydraulic, or electromagnetic.
The role of the control mechanism is to provide the control power to simply force or release
(engage or disengage) the friction discs against each other. Figure 3.31 shows the concept
of a multi disc clutch. If either one of the shafts is fixed, it functions as a brake. If a hydraulic
mechanism controls the fluid flow to the piston chamber to regulate the pressure, then we
control the friction between the discs that connect the shafts to each other. The fluid flow,
which is controlled in such a way to as regulate the pressure, is controlled by an electro-
hydraulic proportional valve where the current applied to the valve solenoid will result in
a proportional pressure. In clutch/brakes, where the transmitted torque is proportionally