Bock Compressor
Parts Supplier
Open-drive reciprocating refrigeration compressors · shaft seal, valve plate and ring set
What a Bock compressor plate actually names
Bock reciprocating compressors, open type and semi-hermetic alike, are identified from the type and machine number on the compressor's own plate, not from the plant or panel they are fitted to.
Open-drive reciprocating units
Bock's open types carry F or FK at the start of the designation, and an ammonia version of the F range is marked NH3; the motor is separate and the crankshaft passes through a shaft seal. That seal is the wear item an open machine adds over a semi-hermetic one, and it belongs on the request beside the valve plate, gaskets and ring set. Quote from the compressor type stamped on its own plate rather than from the unit or cabinet nameplate.
Why an open-drive machine adds one more wear item
A semi-hermetic frame carries its motor inside the compressor body, so nothing passes through the casing and there is no shaft seal to renew. An open-drive Bock unit has the motor outside, and the crankshaft exits through a seal that a semi-hermetic design has no place for. That seal is ordered by its own reference, not assumed from the valve plate or gasket set, and a worn one is usually what an inspection is checking for first on an open machine. It sits where the crankshaft leaves the compressor body for the drive coupling, and wear usually shows first as an oil stain around the coupling guard or a slow refrigerant charge loss between services rather than as an obvious fault; it is then ordered as a set with its O-rings, not as a single face.
Reading a Bock compressor plate
Bock is a long-established German maker of open and semi-hermetic reciprocating refrigeration compressors. It was part of GEA Group as GEA Bock GmbH from 2011, was sold by GEA to the investor NORD Holding and became BOCK GmbH in 2021, and has belonged to Danfoss since 1 March 2023, where BOCK continues as a compressor brand. On board, the compressor type and machine number on its own plate are what identify the specific unit and its spare-parts range, regardless of which owner's branding appears on the label.
An open-drive Bock machine is quoted by its own plate, not the plant name
The type stamped on the compressor's own plate is what actually opens a Bock enquiry — the plant or cabinet name it serves is not enough on its own.
A Bock compressor is identified from the type and serial stamped on its own plate, not from the refrigeration plant or panel it is fitted to. Because the motor sits outside the compressor body on an open-drive machine, the shaft seal is part of the identity too: naming it separately from the valve plate and gasket set keeps a request from bouncing back with a clarifying question.
Ownership of the Bock name has changed three times since 2011 without changing how the compressor itself is read: GEA Group ran the business as GEA Bock GmbH from 2011, GEA sold it to NORD Holding and it became the independent BOCK GmbH in 2021, and Danfoss took it over on 1 March 2023, keeping BOCK as a compressor brand. A plate may therefore read Bock, GEA Bock or BOCK GmbH on the same type — the compressor's own plate is still the reference, not the branding on a data sheet.
What a Bock open-drive request resolves to
Grouped by wear group, because a shaft seal is ordered differently from a valve plate even on the same compressor.
- Shaft seal for the open-drive crankshaft passage
- Valve plate and reed/valve assembly
- Gasket sets for the compressor body
- Piston and ring sets
- Bearing sets
- Oil pump items
- Complete overhaul kits by compressor type and serial
The shaft seal and the valve plate are what an inspection checks first on an open-drive Bock unit — naming the compressor type and serial before the rest of the list keeps a request from returning with a question.
Plate data that makes a Bock enquiry quotable
The compressor's own plate is the fastest route to a correct match. With the items below an enquiry can usually be priced in one pass; without them it comes back with a clarifying question first.
- Full type designation from the compressor's own plate: HG or HA at the start means semi-hermetic, F or FK means open type, and an X after those letters marks a factory ester-oil charge
- Machine number and the oil type filled at the factory, both printed on the Bock plate
- Refrigerant in use
- Which items are needed from the shaft seal, valve plate or ring group
- Photograph of the compressor plate and of the part being requested
Tools for this equipment: the refrigerant number reader for the refrigerant named on the plant and compressor plates. Where an open-drive machine of this kind serves an air-conditioning plant, the air flow and duct calculator gives the air flow a space needs for its sensible load and the duct size for a velocity taken from the air handling design.
The refrigerant is on this list because it decides the material, not just the size: a shaft seal and a gasket set for an ammonia machine are not the same items as for a halocarbon one, so the refrigerant is confirmed before either is put on the quotation.
A shaft seal and a gasket set are not answered alike
Requests naming Bock compressor components arrive mixed, and the review differs by whether the shaft seal of an open-type unit is among the items named, since it is matched to the compressor type and the refrigerant rather than taken from a generic gasket list.
On an open-type machine the shaft seal goes to an OEM-route review by default: a leaking seal loses refrigerant and oil, and the seal is matched to the compressor type and the refrigerant in service, so the plate data and the refrigerant are confirmed before a reference is put against it. On a semi-hermetic HG or HA unit there is no shaft seal to order.
Valve plates, gaskets, piston and ring sets and bearing sets are ordinary supply questions, and a verified alternative can be reviewed on them where a buyer's approval requirements allow, with dimensional and material documentation checked at RFQ stage. Vessel Core is an independent spare parts supplier and marks the proposed route against each line on the list, so a mixed request naming both kinds of item is answered by line, not as one blanket route.
Bock compressor parts — questions from the engine room
What is an open-drive Bock compressor?
Bock builds reciprocating compressors in two forms. On the open types, whose designation starts with F or FK, the motor or drive sits outside the compressor body and the crankshaft passes through a shaft seal. On the semi-hermetic types, starting HG or HA, the motor is inside the casing and there is no shaft seal. The first letters of the type on the plate tell which one is fitted.
Why does an open-drive Bock machine need a shaft seal ordered separately?
The shaft seal is the wear item an open-drive machine adds over a semi-hermetic one, since nothing passes through the casing on a semi-hermetic design. It belongs on the request beside the valve plate, gaskets and ring set rather than being assumed from them.
What parts are ordered on a Bock compressor request?
Shaft seal, valve plate and reed assembly, gasket sets, piston and ring sets, bearing sets and oil pump items are the recurring lines, priced from the compressor type and serial stamped on its own plate.
Has Bock changed ownership?
Yes, more than once. Bock was part of GEA Group, trading as GEA Bock GmbH, from 2011; GEA sold it to the investor NORD Holding, and it became the independent BOCK GmbH in February 2021. Danfoss acquired it with effect from 1 March 2023, and BOCK continues as a compressor brand within Danfoss. The compressor's own plate, not the branding on a data sheet, is what identifies the unit on board.
Can a Bock compressor part be identified without a part number?
Often yes. The decisive evidence is the compressor type and serial stamped on its own plate, together with a photograph of the removed item beside the nameplate. A part-book page or an earlier order line for the same unit is equally usable as reference.
Is Vessel Core connected to Bock?
No, and there is no agreement of any kind. Vessel Core holds no dealership, distribution, representation or partnership agreement with Bock, and quoting a component against one of its designations implies no approval by the maker and no claim of interchangeability.
Submit your RFQ now.
Send the compressor type and serial from its own plate, regardless of whether the label reads Bock, GEA Bock or Bock GmbH, along with the refrigerant and oil in service. Note whether the shaft seal is included in the request, since it is the wear item an open-drive machine adds over a semi-hermetic one.
