Title: Hydraulic actuators: cylinders
1Hydraulic actuators cylinders
Double acting piston
Single acting work can be done only in one
direction
Work is done in both directions
Plunger
Piston rod on both sides
Piston
Tandem
Fast moving
Telescopic
Telescopic
Fast moving
2Hydraulic cylinders
Hidraulikus munkahengerek Rögzítopálcás kivitel 1.
Rögzítopálcás hidraulika henger, a hengerfejen
található karimás rögzítéssel
3Hydraulic cylinders
Hidraulikus munkahengerek Hengeres kivitel 1.
Hengeres építési móddal készült hidraulika henger
4Hydraulic cylinders
The cylinders have to be good quality steel with
close tolerances. There have to be good sealing
both at the piston rod and at the cylinder. With
time dirt may come in and damage the surfaces.
This has to be possibly reduced. In this case,
the leakage will increase all the time.
5Hydraulic cylinders
friction forces
inertial forces
maximum load
slow motion, can be often neglected
Outward
Backward
6Hydraulic cylinders
- Stick-slip
- Transition
- Normal behaviour
Hydraulic cylinders should be possibly operated
in the 3rd region for smooth operation. If the
cylinder is new, the leakage losses are
negligibly small so that ?c ?mech
at higher pressures
7Hydraulic cylinders
Maximum permissible force
n safety factor 1-3,5 lk buckling length I1
moment of inertia of the piston rod E elasticity
modulus of the rod material
8Hydraulic cylinders
A hard impact of the piston at the end surfaces
has to be inhibited kinetic energy has to be
absorbed. This is done by increasing the
hydraulic resistance at the end of the stroke.
9Rotary hydraulic actuators
- Swivel vane rotary actuator
Parallel piston rotary actuator
Limited angle in both directions Maximum angle
always smaller than 360 The same torque in both
directions
Párhuzamdugattyús lengohajtás
Limited angle rotary actuator
Limited angle rotary actuator
Piston rotary actuator
With rack and gear coupling Here maximum angle
may be larger than 360
Mindkét irányban azonosan muködo hengerrel és
fogasléces meghajtással muködtetett tolódugattyús
lengohajtás
Forgódugattyús lengohajtás menettel muködtetett
meghajtócsappal
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10Big pictures
- End of normal presentation
- Beginning of big pictures
11Hydraulic cylinders
smaller force, better efficiency, axial support
is necessary but cylinder does not have to be so
good quality
Without inner buffer
With inner buffer (pilot piston)
12Hydraulic cylinders
- Cylinder types piston, single acting,
pressing-cylinder
Spring
inside
outside
13Hydraulic cylinders
- Cylinder types piston, single acting, puller
Spring
inside
outside
14Hydraulic cylinders
- Cylinder types piston, double acting
Velocity is different
15Hydraulic cylinders
- Cylinder types piston, double acting
- Piston rod on both side
Velocity is the same in both directions
16Hydraulic cylinders
- Cylinder types piston, double acting
- Piston rod on both side
Velocity is different in the two directions
depending on cross section ratio of the rods
17Hydraulic cylinders
- Cylinder types double acting piston, tandem
18Hydraulic cylinders
- Cylinder types single acting, fast moving
19Hydraulic cylinders
- Cylinder types double acting, fast moving
20Hydraulic cylinders
- Cylinder types telescopic, single acting
Large working paths or limited space
21Hydraulic cylinders
- Cylinder types telescopic, double acting
Large working paths or limited space
22Hydraulic cylinders
Eulers cases
1. Case One end free One end fixed Or trunnion
at end
2. Case Two ends pivoted and guided
3. Case One end guided and pivoted, other end
fixed
4. Case Two ends fixed and guided
Picture
Free buckling length
mounting style
mounting style
mounting style
mounting style
Manner of end fixing
Note
23Hydraulic cylinders
- Piston
- Cushion nose
- Cylinder cap
- Stroke volume
- Cushion orifice
- Throttle
- Cushion adjustment screw
- Mother
- Non-return valve
- Gas valve
24Rotary hydraulic actuators
- Parallel piston rotary actuator
25Rotary hydraulic actuators
26Rotary hydraulic actuators
- Rack-and-pinion piston-type rotary actuator
27Rotary hydraulic actuators
- Limited angle rotary actuator
28Rotary hydraulic actuators
- Limited angle rotary actuator
29Rotary hydraulic actuators