Aeroflex Motor Mount MBX3-350

Aeroflex MBX3-350 bronze vibration isolator motor mount with a threaded stud and a bonded rubber element, red-stamped RB3-350 on the isolator. Aeroflex builds elastomeric isolation mounts for rotating and reciprocating equipment.

Isolator mounts sit between a motor or a machine foot and its base, and the rubber element absorbs the vibration that would otherwise transmit into the structure and loosen fasteners. Standard duty on electric motor bases, blower and fan assemblies, compressors, pumps, and instrument cabinets where noise and vibration transfer are the complaint.

New in box; clean bronze with no corrosion or wear. 177 available; price is per mount.

New surplus, available from King Surplus inventory in Del Rio, Texas.

• Part markings, verbatim, read from the record's 8 photographs: MBX3-350 stamped on the body; RB3-350 stamped in red on the elastomer element. Further stamped codes are present on the flange arms but are illegible or mirrored in every photograph.
• Type: Restrained elastomeric vibration isolator / mount
• Construction, as visible in the photographs: cast body with a bonded elastomer element, a threaded centre stud and a bolted-through flange. The casting photographs as bronze or brass in colour.
• Manufacturer: NOT ESTABLISHED. The record carries "Aeroflex" (FID 56), but no manufacturer name is legible anywhere on the part in any of the 8 photographs, and no Aeroflex isolator or mount product line could be found in published sources - searches on the Aeroflex name return EPDM pipe insulation and unrelated corporate pages, not vibration mounts. Treat the manufacturer field as unverified.
• Part number, what is published: MBX3-350 matches, exactly and at the load point, a published product of a different maker. The VMC Group (Vibration Mountings & Controls, 113 Main Street, Bloomingdale, NJ 07403) publishes a spec sheet titled "Model MBX3 350-1300 lbs. Restrained Elastomeric Isolator", and its MB-series replacement elastomer elements carry RB part numbers of the same form as the RB3-350 stamped on this unit. That is a strong match on the number, and it is NOT proof of origin: nothing on the part itself names any maker.
• Published VMC Group MB-series data, given here as the likely reference and NOT as a verified spec of this unit: static load range 30 to 1300 lb across the series; natural frequency 12 to 15 Hz at maximum rated load; operating temperature -20 deg F to +180 deg F; MB1 and MB3 housings heat-treated cast aluminium; hardware zinc-plated carbon steel; elastomer element resistant to oils, ozone and most solvents; supplied as a complete assembly with a built-in levelling device. Named applications: avionics, camera systems, engine controls, communications equipment and weapons systems on rotary-wing aircraft.
• Open discrepancy: VMC gives the MB3 housing as cast aluminium, while this casting photographs as bronze or brass. A gold or yellow chromate finish on aluminium would read that way in a photograph, but that is a guess, not a finding. The material has not been established.
• Rated load: NOT ESTABLISHED for this unit. The 350 in the part number lines up with the bottom of the published MBX3 350-1300 lb range, but nothing on the part states a load rating.
• Spec Basis: rewritten 2026-09-16. Verified against all 8 photographs on this record, which give the two stamped numbers and nothing else, plus VMC Group's published MB-series catalogue page for the part-number match. CORRECTED: the previous entry stated "Manufacturer: Aeroflex" as fact, described the body as "Bronze" as fact, and listed an application line (electric motor bases, blowers and fans, compressors, pumps, instrument cabinets) that appears in no source for this part number - the only published applications for an MBX3 are aerospace. It also carried "Dimensions (packaged): 4 x 7 x 8 in" and "Weight: 4 lb", which are read straight off our own King Surplus yellow tag (L:4 / W:7 / H:8 / Wt:4) and are King Surplus packaging figures, not manufacturer specifications; they have been taken out of this field. TO CLOSE OUT, and this matters because this is the largest unverified value in the batch: photograph the flange stampings square-on and under raking light to recover the maker's name, and settle whether the housing is aluminium or a copper alloy. Until then the manufacturer, the material and the load rating are all open.