Thieves broke into a Ripley engineering firm and stole a power saw and a rock breaker.
The burglary happened at RD Geeson, in Hammersmith, between 5.30pm on Friday May 16 and 8.30am on Monday.
Police say the compound on the industrial estate was locked and whoever is responsible climbed over a fence before getting into a unit and taking the JCB rock breaker and drills, which were manufactured by Makita and Sithl.
A police spokesman said: “Because of the size and weight of the items stolen we believe the burglars would have needed a vehicle to take them away.”
Anyone with information should call 101.