When a high pressure brake line or Power Steering line is disconnected near the pistons or any where besides reservoir. air may get into the system. the only way to get the air out of the system is by bleeding system, or purging system. if not done the result will be spongy brake's squealing and whining sounds when turning.
The only thing that causes hydraulic fluid to foam is air. The solution as to why your hydraulic system is creating air can be difficult. If the system has a hydrostatic drive , then there will be a charge pump( gear or georoler) which will always be working off of the hydrostatic pump in a vacumn state. This is where 90% of air introduction occurs. The easiest way to find the leak will be to notice any damp spots around the hydrostatic pump, usually at input shaft areas of any sort to the pump. The effect is a noisy, jumpy hydraulic action. Extended use while oil is aerated can cause damage to the pumps. If it is a regular hydraulic system them air will again be introduced on the inlet side of the pump, due to bad hoses, clamps, clogged inlet filter or low or overfull system
Any air compressor that can achieve and hold 100psi will run an air gun. the larger the tank the more lugs you can remove before the compressor will need to run again.
There is a leak in the brake hydraulic system and the brake fluid has leaked out of the master cylinder enough to induce air into the system and result in no pressure in the braking system. This is too dangerous of a situation to drive on. A vehicle in this condition needs to be towed somewhere to be repaired. Likely a brake line or hose has ruptured and has leaked out a majority of the fluid. Also it is common for a caliper or wheel cylinder to leak, especially if the brakes have been grinding for a while and now suddenly there is no pedal pressure. All parts of the hydraulic system need to be inspected for leaks and repaired properly.
Need to know what your question is.
Just make it snug with an open end wrench and bleed the line to remove air (make sure fluid reserve does not get low while bleeding).
Air in the hydraulic fluid
one reason air is much harder to control the heat and air has a lot of water in it and a hydraulic system dose not need water in the hydraulic oil. There is no way at the high pressure that a hydraulic system has to work at,it would not be possible to control the heat.
Bleeder valve: Valve, usually operated by a wrench, to release the air from a hydraulic system EG: Hydraulic brakes or Diesel engine injection systems or Early gasoline fuel injection systems or Cooling systems or many other applications that you need to remove air from fluid systems.
Then you need to bleed the brake system to remove the air.
it involves air
That would be "bleeding" the system.
Air in the system.
Bleeding
Air in the lines
An air chamber is a chamber in a hydraulic system in which air is compressed to regulate the flow of a fluid.
Transmission fluid is performed by the hydraulic system. Pneumatic power transmission system is done by the gas.
air in the hydraulic brake system