Roley was the fourth machine to join Bob's team, but it said he was the fifth in When Bob Became A Builder. Before he joined, Bob and the three machines were building a road using concrete. However, after they had finished, the road's surface was bumpy. Bob used his hand roller and the machines tried running over the concrete to flatten out the road, but it did not work. Luckily for them, Bird saw the situation and went to get his friend, Roley. Soon Roley arrived and and told the team that they needed some rock and roll. Bob replied that that they were fine from music, but Roley meant it as in flattening. Soon, he got to work, making the road's surface smooth and flat. After that, he joined the team.
Roley is a heavy, cheerful machine who can get excited and loves to "rock and roll"! He's shown to be very musical and usually makes up songs and he even sings them during work. He spins his eyes when he's excited and is also fond of animals.
Roley is green with a silver bell-shaped mouth. His rollers were dark grey in the stop motion era but were changed to black when the show transitioned into CGI in the Ready, Steady Build! spin-off. He has an orange-yellow warning light on his cab.
Roley resembles a Zettelmeyer diesel road roller which were built between 1931 to 1978.
In 2003, Jolly Roger (Amusement Rides LTD) made him as a kiddie ride that says three different phrases, including: "Rock n Roll!", "Oh! That is really cool, Bob!", and "Can we fix it? Yes we can!", and plays the Bob the Builder theme tune. Also, in 2004, Jolly Roger made him as another kiddie ride, but this time with a video screen (normally there's a windscreen on the front). There are 2 push buttons on his dashboard (video option, one push button if standard). One button says "Rock n Roll!", whilst the other button says "Oh! That is really cool, Bob!".
Roley's movement sound effect is simply his front roller moving over the ground. This effect is heard regardless of the surface he is on. This rolling sound wasn't used in the Ready, Steady, Build! series.
Roley's US voice in the original series sounds similar to a young boy's voice.
Roley is male in all dubs, but is female in the Swedish dub.
Like Lofty, he is voiced by female voice actresses in the US dub, even though Roley is a male.
Roley appears to like rapping as seen in Roley's Weather Rap.