BackgroundThe story
The 15-91 belongs to one of Singer’s longest families. Singer began the Improved Family machine in 1879; in 1895 it was reworked and the Singer 15 was born (singersewinginfo). The class went on to become, in singersewinginfo’s words, “the most successful sewing machine design ever”.
The 15-91 added a type PG potted motor built into the back of the pillar. It drives the machine directly through internal gearing (singersewinginfo). Spoolofthought calls this direct gear drive a major advance: the motor’s gears link straight to the machine’s gears, with no belt to slip. Spoolofthought and tallysew both give production as 1930 to 1956, and tallysew notes it was made in the United States and Canada.
Tallysew says the 15-125 replaced it in 1955. ISMACS describes the 15-125 as a 15-75 with a built-in potted motor, made 1955–1958. So if you find a later Class 15 with a motor on the back, check the model number before you assume it’s a 15-91.
ReferenceSpecification
Specification plate
- Years made
- 1930–1956 (spoolofthought and tallysew). The Class 15 family as a whole ran for over a century.
- Factory
- Elizabethport, New Jersey (the hyphenated model number indicates Elizabethport). A 15J91 made at St Johns, Canada, is also recorded.
- Size and bed
- Full-size flatbed, low shank. Usually fitted in a cabinet.
- Hook and bobbin
- Oscillating hook, Class 15 bobbin in a bobbin case.
- Needle
- 15x1 (also sold as 2020 or 130/705H). Threads left to right.
- Drive
- Potted motor mounted on the back of the pillar, driving the machine through internal gears — no belt.
- Stitches
- Straight stitch with reverse and drop feed.
IdentificationHow to recognise a 15-91
- Motor on the back: a round motor housing sits on the back of the pillar, with no belt running to the handwheel.
- Tension on the faceplate: on Class 15 machines the upper tension is built into the faceplate above the presser bar.
- Solid handwheel.
- Bobbin case finger at about 11 o’clock.
Pungolivinghome names the 15-91, 101 and 201 as Singer’s gear-driven potted-motor domestics; ISMACS also lists the later 15-125 with a built-in potted motor.
The motor housing has grease cups closed with thumb screws. The manual says these take Singer Motor Lubricant, never oil.
Look for the brush tubes with end covers on the motor. The manual tells you to remove these to clean the carbon brushes.
Spoolofthought lists a moulded Singerlight as standard. It takes a push-and-twist bulb that locks with a pin in a notch.
Singersewinginfo lists the 15-91 as a domestic, reverse-feed, potted-motor machine. The adjuster’s manual calls it a “reversible feed” family machine.
The feed dog is raised or lowered with a thumb screw under the bed, not a lever on top (adjuster’s manual).
VersionsVersions and sub-models
| Version | What sets it apart |
|---|---|
| 15K91 | Listed alongside the 15-91 by singersewinginfo with the same potted-motor description. |
| 15J91 | The Canadian-made version; tallysew confirms the 15-91 was built in both the US and Canada. |
Parts and accessoriesBobbins, attachments and the parts it takes
The original Simanco part is 125291, with the finger pointing left at 11 o’clock. Old Singer Shop warns it is not compatible with all Class 15 machines, so check the finger position before you buy a spare.
Flat-sided Class 15 bobbins go inside the removable bobbin case. Don’t confuse them with Class 66 bobbins, which drop straight into a 201 or 66.
The grease cups take Singer Motor Lubricant, sold in tubes. The manual says to squeeze about a quarter of a tube into each cup.
The manual gives part No. 191120 and says the bulb’s voltage must match your supply.
Parts suppliers sell replacement grease wicks, wick springs and clips for potted motors, listed for the 15-91, 15-125 and 201-2.
MaintenanceLooking after it
Remove the thumb screws, clean out the cups and squeeze in about a quarter of a tube of Singer Motor Lubricant. The manual says: “Never, under any circumstances, use oil in the grease cups or on any part of the motor.”
Oil the shuttle race, the connecting rod wick and the bearing points marked in the manual. One drop of sewing machine oil at each point is sufficient.
Take off the end covers and wipe the carbon brushes, the inside of the brush tubes and the covers with a clean, dry cloth (adjuster’s manual).
Restorers of the closely related 201-2 motor clean the grease wicks, then soak them in melted grease so they absorb it again (pungolivinghome).
When you refit the bobbin case, make sure its positioning finger sits in the notch of the position plate (manual).
General advice from the sources listed below. If in doubt, follow your machine’s Singer manual.
Before you buyWhat to check on a used 15-91
In-person checks
QuestionsFrequently asked questions
What’s the difference between a 15-91 and a 201-2?
Both have gear-driven potted motors. The 15-91 uses an oscillating hook and Class 15 bobbin in a bobbin case; the 201-2 uses a full rotary hook and a Class 66 drop-in bobbin.
What bobbin case fits a Singer 15-91?
The original is Simanco 125291, with the finger at 11 o’clock. Sellers list it for the 15-88, 15-89, 15-90 and 15-91, among others.
What grease goes in a 15-91 motor?
Singer Motor Lubricant, about a quarter of a tube per grease cup. The manual is firm that oil must never go in the grease cups or on the motor.
What replaced the Singer 15-91?
Tallysew says the 15-125 replaced it in 1955. ISMACS describes the 15-125 as having a built-in potted motor, made 1955–1958.
Can a 15-91 sew denim or leather?
Spoolofthought says the direct gear drive lets it power through thick materials such as denim, canvas and leather.
Are 15-91 parts interchangeable with other Singer 15s?
Tallysew says many 15-91 parts, such as the bobbin winder and balance wheel assembly, generally swap with other model 15 machines, though there can be variation by year.
ReferencesSources
Where sources disagree we show each figure rather than choosing one. Spotted an error? Tell us.
- ismacs.net/singer_sewing_machine_company/singer-15-91-sewing-machine.html
- singersewinginfo.co.uk/15
- www.spoolofthought.com/1591-improved-family
- ismacs.net/singer_sewing_machine_company/p15.html
- www.singersewinginfo.co.uk/15
- tallysew.com/sewing-machines/singer-sewing-machines/singer-15-91
- www.manualslib.com/manual/1027731/Singer-15-91.html
- oldsingershop.com/products/singer-class-15-sewing-machine-bobbin-case-original-simanco-125291-15-88-15-90-15-91
- www.penelope.ca/us/bobbin-case-singer-15-88-15-91.html
- www.vintagesingerparts.com/products/singer-potted-motor-parts-fits-15-91-15-125-201-2-sewing-machines
- pungolivinghome.com/2022/04/04/restoration-of-a-vintage-centennial-singer-model-201-2
Last reviewed October 2026