Week #14: Hydraulic Valves, Cavitation, Work, Power, Torque & RPM
Posted: Fri Apr 26, 2019 8:10 am
Hydraulic Directional Control Valves
Normally Open vs. Normally Closed Valves
Cavitation
Related to cavitation, Water Boiling in a Vacuum Chamber.
We watched this earlier in the semester but it applies in part to our discussion of cavitation, Peeps in a Vacuum Chamber. On the shaving cream demo, notice that when atmospheric pressure is restored (a high pressure compared to the vacuum) the small bubbles of air collapse violently, an implosion, which is rather forceful (for shaving cream). The same happens when the bubbles created under cavitation implode against the impeller and pump mechanism. This can lead to rapid pump failure. One of the purposes of the normally closed relief valve in a hydraulic system is to provide a path of fluid flow when back pressure gets too high in the system. This allows the fluid to return to the cooler reservoir rather than become rapidly heated in the high pressure condition. As was mentioned, when the fluid heats up, cavitation is more likely to occur.
The first few slides of: Work and Power
What is Torque?
Calculating Horsepower, RPM & Torque. This presentation has sound.
Here are some Basic Mechanics Word Problems. The first couple reflect some of the content presented above.
NOTE: Next Friday, May 3, we will be taking our field trip to TTM in Stafford Springs, CT.
Additional Final Exam, Lab Manual & End of the Year Information can be found by clicking here.
Normally Open vs. Normally Closed Valves
Cavitation
Related to cavitation, Water Boiling in a Vacuum Chamber.
We watched this earlier in the semester but it applies in part to our discussion of cavitation, Peeps in a Vacuum Chamber. On the shaving cream demo, notice that when atmospheric pressure is restored (a high pressure compared to the vacuum) the small bubbles of air collapse violently, an implosion, which is rather forceful (for shaving cream). The same happens when the bubbles created under cavitation implode against the impeller and pump mechanism. This can lead to rapid pump failure. One of the purposes of the normally closed relief valve in a hydraulic system is to provide a path of fluid flow when back pressure gets too high in the system. This allows the fluid to return to the cooler reservoir rather than become rapidly heated in the high pressure condition. As was mentioned, when the fluid heats up, cavitation is more likely to occur.
The first few slides of: Work and Power
What is Torque?
Calculating Horsepower, RPM & Torque. This presentation has sound.
Here are some Basic Mechanics Word Problems. The first couple reflect some of the content presented above.
NOTE: Next Friday, May 3, we will be taking our field trip to TTM in Stafford Springs, CT.
Additional Final Exam, Lab Manual & End of the Year Information can be found by clicking here.