Hydraulics

Question 1

Describe the hydraulic system

Answer 1

Composed of 2 independent systems
- 3 double-cylinder servo actuators, upper and lower portions

System 1: supplies to the 3 upper cylinders
System 2: supplies to the 3 lower cylinders

Question 2

What is the total volume of the hydraulic system?

Answer 2

2.2L

Question 3

What is the normal pressure of the system and how is it maintained?

Answer 3

Regulating valves keep constant pressure at 35 +/- 1 bar

Question 4

What do each system have in it?

Answer 4

• separate hyd reservoir
• magnetic drain plug w/ strainer
• single constant flow rate pump
• filter with visual clogging indicator, low pressure switch, regulating valve maintains pressure at 35bar

Question 5

What drive the pumps? Where are they located?

Answer 5

System 1 (upper)
- ABEX drive pump driven by the bevel ring gear of the MGB
- mounted forward lower side of the MGB

System 2 (lower)
- driven by a poly V belt on the engine drive shaft
- right side of transmission

Question 6

Which system has pipes installed rigidly into the MGB upper housing?

Answer 6

System 2 (lower)
Seen on the right side of the transmission

Question 7

Where are the Hyd units located?

Answer 7

System 1 (upper) forward upper side of the MGB
System 2 (lower) right side of the MGB, near the pump for system 2

Question 8

Where are the reservoirs located?

Answer 8

Mounted together on the aft upper side of the MGB. Rubber shims prevent friction. Sight glasses on the right side for both
- System 1 (upper) is the aft reservoir
- System 2 (lower) is the forward reservoir

Question 9

Both pumps deliver what rate?

Answer 9

Constant flow rate of 6 L/min at 6000RPM

Question 10

At what point do the HYD and SERVO lights go out on start?

Answer 10

At 26 +/- 2bar of pressure in the systems

Question 11

At what point are the lights activated in a low pressure situation?

Answer 11

20 bar

Question 12

How can you tell which system has failed in the B4?

Answer 12

System 1 = HYD, SERVO, LIMIT
System 2 = HYD and SERVO only

Question 13

Where is the limit switch located?

Answer 13

Top of upper right later servo

Question 14

Describe structure of the Hyd Units

Answer 14

• Top of unit is the Pressure Regulating Valve
• Mid unit is the Pressure Switch sticking out
• Mid unit below the switch is the LRB
• Bottom of unit is the filter

Question 15

How many double rotary distributor valves are part of the system?

Answer 15

6 total
- one on each of the servos, both upper and lower

Question 16

What is the purpose of the double distributor valve?

Answer 16

Safety feature - removes possibility of a single slide valve seizure

Question 17

What happens when one of the double distributor valves jams?

Answer 17

• If the primary valve jams (outer valve) it forces the secondary valve (inner valve) to rotate
• SERVO light illuminates

Question 18

What parameter for flight should you follow when you have a loss of hyd pressure?

Answer 18

Bank < 30 degrees
Airspeed < 110 kts