Brother HL-1040 - Manual (Page 116)

A-20
APPENDIX 19. DIAMETER / CIRCUMFERENCE OF ROLLERS
The diameter and circumference of each roller are listed below;
No. Parts Name Diameter (Circumference)
1 Paper Feed Roller 
11.97 mm (37.6 mm)
2 Transfer Roller  16.90 mm (53.1 mm)
3 OPC Drum 
29.97 mm (94.1 mm)
4 Heat Roller  19.86 mm (62.4 mm)
5 Pressure Roller

16.50 mm (51.8 mm)