To Non-Java ALLSTAR Network Website
Please let me remind all of you--this
material is copyrighted. Though partially funded by NASA, it is still a
private site. Therefore, before using our materials in any form, electronic or
otherwise, you need to ask permission.
There are two ways to browse the site: (1) use the search button above to find specific materials using keywords; or,
(2) go to specific headings like history, principles or careers at specific levels above and click on the button.
Teachers may go directly to the Teachers' Guide from the For Teachers button above or site browse as in (1) and (2).
As the liquid comes from the reservoir, it is pushed between the gear teeth. The oil is
moved around to the other side by the action of the drive gear itself and sent through the
pressure line. What makes the oil squeeze in between the gear teeth? gravity and the
pressure head. To prevent leakage of oil from the high to the low pressure side from
occurring, you can make the gears fit better.
You might want to increase the pressure used to move the fluid along. However, the higher the pressure, the higher the friction loading on the teeth. Friction will develop heat which will expand the gears and cause the pump to seize (parts will weld together and gears will stop rotating). In order to stop this, you can have the pump case, the gears, and the bearings made out of different materials, (e.g., steel gears [1-1/2 inch thick], bronze bearings, aluminum casing). Normally, the gear speed is higher than the engine speed (normally 1.4 times the engine speed).
Oil can leak over and under the gears. To prevent leakage, you can press the bearings up against the gears. This decreases seepage but this decreases the mechanical efficiency when friction increases. Even though oil acts as lubricant, seizing can occur when oil is drained from the hydraulic system.
Volumetric efficiency is due to the number of teeth, the area of each tooth and the engine speed.
If you don't see the animation, click here to download Macromedia Shockwave Player.
Send all comments to firstname.lastname@example.org
© 1995-2018 ALLSTAR Network. All rights reserved worldwide.
Updated: March 12, 2004