Phrase Variations
- Put a spanner in the works
- Throw a monkey-wrench in the works
A spanner in the works is an event or action that interferes with a process. A spanner (British English) or monkey-wrench (American English) is a tool used to work on machines—to tighten bolts. Works can mean machines, factories, or other complex systems. However, one can also use a more specific description of the works:
The bad weather threw a monkey-wrench in our plans for a picnic.
The business was ready to open but supply problems threw a spanner in the works.
My program isn’t working correctly; there must be a spanner in the works.
Although spanners and monkey-wrenches are normally used to fix machines, in this case, we imagine accidentally dropping the tool into a machine, or throwing the tool into the machine where it interferes with moving parts.
This phrase may have been inspired by industrial sabotage. Workers almost never accidentally drop tools into machines—but purposely doing so is a well-known method for sabotage. Notice that the phrase says throw or put, not drop or lose.
Inspired by the industrial revolution, this phrase appeared by 1930, and perhaps earlier, in the 19th century. During the industrial revolution in America, there were many protests of workers against the dangerous and inhumane working conditions.