Randy Bachman was the guitarist for Canada's first hard-rock band, the Guess Who, formed several years before the term "hard-rock" was coined. When hard-rock became fashionable, they recorded three albums, Wheatfield Soul (RCA, 1969), Canned Wheat (RCA, 1969) and American Woman (RCA, 1970), that established them among the premier hard-rock acts in the world (respectively These Eyes, Undun, American Woman). 
Bachman left Guess Who to launch his solo career, with Axe (RCA, 1970), and to form his own band, Brave Belt, which recorded two albums, I (1971) and II (1972). When bassist Fred Turner joined the band, the Bachman-Turner Overdrive was born. Their first album with the new name, Bachman Turner Overdrive (Mercury, 1973), offered solid boogie. II (Mercury, 1974) was heavily influenced by the Who (Takin' Care Of Business). Not Fragile (1974), their masterpiece, contains You Ain't Seen Nothin' Yet and Roll On Down The Highway. After the mediocre Four Wheel Drive (1975), the band tried to reinvent itself on Head On (1976), which couples traditional numbers such as Take It Like A Man with more sophisticated pieces such as Lookin' Out For Number One. After Freeways (1977), Bachman left the band and launched a new project, Ironhorse, which released Ironhorse and Everything Is Grey. The band reunited for BTO (Compleat, 1984).
The precursor to BTO was the band Brave Belt, formed in 1970 by Randy Bachman-guitar and Chad Allan-keyboards/vocals (both of The Guess Who), Robbie Bachman-drums and C.F. "Fred" Turner-bass/vocals. An original plan included Keith Emerson of The Nice, though he was dropped due to illness. After two moderately successful Brave Belt albums, Allan was replaced by Tim Bachman, the third of the Bachman brothers, and the band changed its name to Bachman-Turner. Shortly afterward, Randy noticed a copy of a trucker's mazagine called Overdrive in a roadside restaurant, and the name Bachman-Turner Overdrive was born.
BTO released their eponymous self-titled first album in the spring of 1973. The album broke through in the US via border towns such as Detroit and Buffalo, but failed to produce a hit single. http://www.youtube.com/watch?v=fF7ZanvRlLM
On an interview track released with the Live BTO King Biscuit Flower Hour recording (1998), Randy proclaimed that the signing of BTO's first album was a stroke of luck. After the demo tape had been rejected by 26 labels, Bachman was prepared to tell the other band members that they would no longer be able to remain on salary. But in April of 1973, Charlie Fach of Mercury Records returned to his office (from a lengthy stay in France) to find a pile of unplayed demo tapes on his desk. Wanting to start fresh, he grabbed a trash barrel and slid all the tapes into it -- except one, which missed the barrel and fell on the floor. Fach picked up the tape and noticed Bachman's name on it. He remembered talking to Bachman the previous year, and told him that if he ever got a demo together to send it. After playing the first song on the 7-1/2 inch reel ("Gimme Your Money Please"), Fach immediately called Bachman to tell him of his intention to sign the band. http://www.youtube.com/watch?v=QU0SwYK0vco
Their second album, Bachman-Turner Overdrive II, was released in December of the same year and became a massive hit in the US and their native Canada. It also yielded their best-remembered single, "Takin' Care of Business" written by Randy Bachman. BTO were one of the early hard rock bands which opted for songs backed by catchy melodies and powerful riffing. The band also promoted a strait-laced lifestyle due to the Mormon religious beliefs of Randy Bachman.
Tim Bachman left because of limited performance skills and personal lifestyle issues, and was replaced by Blair Thornton. The first album with the modified lineup, 1974's Not Fragile, became a hit, including the #1 single "You Ain't Seen Nothing Yet" and AOR hit "Roll on Down the Highway". The band continued to steadily produce successful albums through the mid-1970s including Four Wheel Drive and Head On (both 1975). http://www.youtube.com/watch?v=oq7HxaAxF78
After the release of Freeways in 1977, Randy Bachman left the group for a solo career and another band, Ironhorse. Randy was replaced by bassist/vocalist Jim Clench, formerly of April Wine. Original bassist Turner moved to rhythm guitar/vocals, with Thornton becoming the primary lead guitarist. This BTO lineup released a pair of albums (Street Action - 1978 and Rock & Roll Nights - 1979) before breaking up. http://www.youtube.com/watch?v=xL0Sw-DH4ak
BTO reunited in the 1980s, leading to a lawsuit between the brothers, as one group, led by Randy, toured as Bachman-Turner Overdrive and another, led by Robbie, toured as BTO (Robbie Bachman, Fred Turner, Blair Thornton, and Randy Murray). Interestingly enough in 1984 the line up for Bachman-Turner's first studio LP in 5 years consisted of Randy and Tim Bachman, Fred Turner and former Guess Who drummer Garry Peterson. In 1986 they were the opening band for the newly reformed Van Halen. By that time Fred Turner had left the band, probably to join the "other" BTO. Robbie Bachman's BTO toured and performed until December 2004. No further plans for the band to appear are currently known, so it would be a reasonable assumption that they have retired from live performances.
Bachman-Turner Overdrive's music lives on today, and continues to be featured in movies and in advertising campaigns. Randy Bachman recently published an autobiography, and "BTO" has been featured more than once in southern humorist Ed Williams' books. Bachman-Turner Overdrive has also been featured on an episode of The Simpsons titled "Saddlesore Galactica." http://www.youtube.com/watch?v=zVMzyct2Ox4