Bulls coach Mick Potter gave Ben Jeffries his first start since he re-joined the club from Wakefield.
Moments later the pair combined again with Dobson providing the pass to Welham for the centre to touch down out wide.
KR then took advantage of weak Bull defence with Blake Green racing through a big gap to extend his side’s lead.
The Bulls hit back straight away with Jeffries finding Gareth Raynor with a cut out pass to reduce the gap.
Shortly after, Green passed for Jake Webster to cross and then Dobson brushed off tacklers to stretch for the line and touch down, giving the hosts a 16 point lead at the break.
The Bulls did hit back through Andy Lynch, the big prop barging over from close range. Jeffries then went close with a great run, but any hope for the Bulls was short-lived after Ben Cockayne put Welham in for his hat trick.
Fox had the final say of the game as he touched down after gathering an offload by Webster. The win see’s Hull KR go above Bradford in the table with the Bulls not recording a win in their last six Super League games.