Page 33 - Fluid Power Engineering

10 Cha pte r O n e

2. High cost of production due to the requirements of small
clearances and high precision production process.
3. High inertia of transmission lines, which increases their re-
sponse time.
4. Limitation of the maximum and minimum operating tem-
perature.
5. Fire hazard when using mineral oils.
6. Oil filtration problems.

1.5 Comparing Power Systems
Table 1.1 shows a brief comparison of the different power systems,
while Table 1.2 gives the power variables in mechanical, electrical,
and hydraulic systems.

System
Property Mechanical Electrical Pneumatic Hydraulic
Input energy ICE and ICE and ICE, electric ICE,
source electric motor hydraulic, motor, and electric
air or steam pressure motor, and
turbines tank air turbine
Energy Mechanical Electrical Pipes and Pipes and
transfer parts, levers, cables and hoses hoses
element shafts, gears magnetic
field
Energy carrier Rigid and Flow of Air Hydraulic
elastic electrons liquids
objects
Power-to- Poor Fair Best Best
weight ratio

Torque/inertia Poor Fair Good Best
Stiffness Good Poor Fair Best

Response Fair Best Fair Good
speed
Dirt sensitivity Best Best Fair Fair

Relative cost Best Best Good Fair
Control Fair Best Good Good

Motion type Mainly rotary Mainly rotary Linear Linear
or rotary or rotary

TABLE 1.1 Comparison of Power Systems