Thomas first encountered Judy and Jerome in a siding at Knapford Station Yard, where they thought there was an emergency after Thomas woke them up. Annie and Clarabel then explained to him what they were for. He later collected them after James' accident with some trucks.
After Rocky arrived and the Search and Rescue Centre was built, Judy and Jerome became obsolete. They remained on their siding at Knapford for several years, eventually being noticed by Ryan. Looking for a change in scenery, they had him take them to Arlesburgh Harbour. However, the sea air caused their gears to not work properly, so they asked Oliver, who was passing by, to move them somewhere else. He took them to a field on the Little Western, but they quickly grew bored there. When Duck passed by, they asked him to move them somewhere else, so he took them to the Blue Mountain Quarry. However, Daisy soon derailed on the other side of the island from the Search and Rescue Centre and Judy and Jerome were missing, meaning that Thomas would have to go all the way to the Search and Rescue Centre from Knapford to get Rocky. However, Ryan was able to track them down and bring them to Daisy. Happy to be useful again, Judy and Jerome were taken to Arlesburgh that night. The Fat Controller then decided to relocate them to Arlesburgh permanently, allowing them to handle emergencies on the west side of the island while Rocky handled the east, having realised the strategic importance of having more than one breakdown train.
Judy and Jerome are both heavy sleepers, but take their jobs very seriously, usually only awaking if there is an emergency (or if they think there is). The two also seem to be very talkative. They are always ready for an emergency and respond with zeal and vigour and enjoy working.
Judy and Jerome are painted dark green-grey with yellow hazard stripes along their sides. They have brass nameplates on the sides of their cabs.
- Season 1 - Harvey's Goods Train (do not speak), Oliver and the Slip Coaches (do not speak), and Snowdrift (cameo)
- Season 2 - Disappearing Diesel, Breakdown Butch (cameo), Sidney Gets Lost, Timothy and the Aquarium (cameo), and Truck Trouble (cameo)
- The Great Storm of Sodor (do not speak)
- Aside from the addition of faces and nameplates, Judy and Jerome differ slightly in design from the original incarnation of the Breakdown Train:
- The cable to raise and lower their crane arms was moved to their roofs, rather than being attached to a smaller arm.
- Their cabs are slightly taller and their crane mechanisms are slightly shorter to accommodate faces.
- They have yellow hazard stripes, which were originally not present.
- Judy is the first female crane in the series.