What can you tell me about the various brake master cylinders used on our planes?
Search strings: brakes, brake cylinder, master cylinder, Paramount, Gerdes, Cleveland.
Technical Editor:
The original 1962-1963 Musketeer brake master cylinder, as used on M0001-M0493, is P/N 169-380006. It can be identified by the lever that traps the main piston rod, to provide the parking brake function. This unit has usually long since been replaced by the later Paramount integral-reservoir unit. The official Beech supersedure is Kit #23-5012, which provides the later Cleveland cylinders with a remote reservoir (and eliminating the shuttle valves).
The only O-ring used in this earliest cylinder is:
AN6227B9 (MS28775-111)
The manufacturer’s cylinder P/N is:
VHR625NL (Pilot’s with PB lever)
VHR625N (Co-Pilot’s without PB lever)
The check valve wafer spring is P/N 3502-14-21-0511, which has been superseded by P/N 3502-14-46 (available from RAPID).
The rod-with-disc check valve assembly is P/N A57G113 (supersedes to A114)
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The earliest Paramount cylinders with the integral reservoir, as used on M0494-M1034, MB001-MB264, and MA001-MA233, are:
A75J (Pilot’s side with integral parking brake valve in cylinder base)
A75L (Co-Pilot’s side without integral parking brake valve in cylinder base)
The O-rings used in this cylinder are:
A106-515
A106-511
I don’t recall the cross-over numbers for these two rings, but I have successfully used standard MS28775 rings to replace them. These cylinders did not use a wafer spring check valve; they had a built-in ball check valve instead, at the base of the cylinder where the brake hose attaches. The official Beech supersedure is Kit #23-5012, which provides the later Cleveland cylinders with a remote reservoir (and eliminating the shuttle valves).
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The first generation of remote-reservoir systems used Paramount master cylinder P/N 96-380024-5, as used on M1035-M1284, MA234-MA363, and MB265-MB480.
The O-rings used in this cylinder are:
AN6227B6 (MS28775-011)
AN6226-B9 (MS28775-111)
AN6227B11 (MS28775-113)
The check valve wafer spring is P/N 3502-18-24-0511, which has been superseded by P/N 3502-18-34. A couple of these are available from Elliott Beechcraft, in Moline.
The rod-with-disc check valve assembly is P/N A57G113 (supersedes to A114)
There is also a rod wiper, P/N A57G401, which attempts to prolong the life of the B6 sealing ring.
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Effective with the (wider and heavier)1970 models came two similar but different versions of Gerdes brake master cylinders. One version has an internal (recessed) snap ring retaining the top cap/plug. The other version has a screw-in top cap, which is safety-wired in place. The two part numbers are 96-380034-11 and 96-380034-13; but I have found those same numbers on both versions. The -13 was supposed to have superseded the -11. Subsequent supersedures were 169-380100-1, then 169-380100-3. The units up through the -1 were all made by Gerdes. Gerdes was sold to Parker-Hannefin, and the 169-380100-3 is a Cleveland 10-55. The Cleveland unit is usually the part installed on all of the 1978 and later production, and is contained in the 23-5012 kit. It is the only cylinder unit in continued manufacture, making it the most desirable (and repairable) unit. It also has the much sturdier 3/8” piston rod; the earlier Gerdes units have the 5/16” rod. None of these contain the wafer spring used in the Paramount cylinders.
The O-rings most commonly found in the Gerdes cylinders are:
96-380034-11:
11-008 (MS28775-008)
11-011 (MS28775-011)
11-014 (MS28775-014)
11-111 (MS28775-111)
96-380034-13:
11-008 (MS28775-008)
2-011 (MS28775-011)
2-016 (MS28775-014)
11-111 (MS28775-111)
The Cleveland 10-55 contains:
MS28775-012
MS28775-111
MS28775-112
Stat-O-Seal 600-001-10
I stock many of these items in my shop, but I cannot offer them for general sale. They are generally very hard to find, can be located only in very small quantities, and I need to have them for members who fly in to have work done here. The exception is that many of the O-rings are readily available in the standard MS28775 sizes.