A 1FK7 is not one motor but a family: SIMOTICS S-1FK7 synchronous servo motors in many frame sizes, speeds and options, built to run on SINAMICS drives. Two of them can share a frame size and a rated speed and still not be interchangeable, because the encoder, the holding brake, the shaft and the degree of protection are all options. Each option is part of the article number.
The article number is the specification
Siemens article numbers (MLFB) code the product in blocks: the family, then the rating, then the options. How to read a Siemens order number explains the structure in general. For a 1FK7 the practical rule is simple: the full number on the rating plate, for example 1FK7063-5AF71-1PA0, defines one motor, and a spare with the same first block and a different last block is a different motor.
Siemens’ own product page for each article number on SiePortal lists what the number stands for: the encoder, the shaft (plain or with a feather key), with or without holding brake, the degree of protection, and the product’s lifecycle status. Look the number up on SiePortal before you buy a spare, and keep a copy of the page.
The encoder decides whether the drive will talk to it
On SINAMICS S120, a 1FK7 with a DRIVE-CLiQ encoder connects straight to the drive and reports its own data. A 1FK7 with a resolver or a sin/cos encoder needs a Sensor Module in between. A spare with a different encoder can bolt on and still need a different module, different cables or a new commissioning of the axis. Before ordering:
- Note the encoder from the rating plate or the product page: the type, and whether it is single-turn or multiturn. A multiturn absolute encoder keeps the axis position through power-off; replacing it with single-turn means homing the axis again.
- Check the brake. A motor without a holding brake on a vertical axis is a safety question, not a convenience.
- Check the shaft and the connector orientation, which decide whether the coupling and the cables fit without changes.
1FK6, 1FT6 and the SIMODRIVE generation
Older machines often carry 1FK6 and 1FT6 motors with SIMODRIVE 611 drives (article numbers starting 6SN11), and SINUMERIK controls (6FC5). They are still widely in service, and often the right fix for one failed motor is the same motor again, not a new drive system. When you do plan a change, check the lifecycle status of every part involved on SiePortal; finding a replacement part explains the PM codes Siemens uses.
Searching Sparehawk for Siemens motion parts
Search by the article number, or by the family prefix when you want to see what is offered across a range:
- 1FK7, 1FK6 and 1FT6 servo motors
- SIMODRIVE 611 drives (6SN11)
- SINAMICS drives (6SL3)
- SINUMERIK controls (6FC5)
Each offer shows its condition (New / OEM, new surplus, refurbished or used), the supplier’s country and the lead time. Search 1FK7, 6SN11 or browse all Siemens parts.
Before you order
- Send the full article number and a photo of the rating plate. If the plate is unreadable, the machine builder’s parts list or the drive’s commissioning project often records the motor.
- Ask about the encoder and the bearings on a used or refurbished motor: what was tested, and whether the encoder was replaced or adjusted. Refurbished, surplus and used explains the conditions, and warranty on surplus parts lists the questions to ask about cover.
If no offer matches the number, send a request anyway: how requests work.