during the first phase of the installation cycle when initial roof bolt torque is built p e 130 lb ft air cylinder 21 has no pressure and the full reaction force available at roller 11 is exerted on the plunger of air pressure regulator 20 under the conditions cited 130 lb ft of torque at the roof bolt head results in an output of 83 psi from regulator 20 and 0 from regulator 19 during the second phase of the installation cycle that of checking decay of torque at the roof bolt head after a brief time lapse air pressure is applied to the cylinder 21 by appropriate sizing of components range compression and expansion may be accomplished if for example c a 0 32 a b 0 80 the bore size of cylinder 21 is 1 5 34 and 60 psi air pressure is applied to cylinder 21 a reaction force of 90 lbs at roller 11 results in an air pressure output of 80 psi from regulator 19 a reaction force of 120 lbs at roller 11 results in an air pressure output of 20 psi from regulator 19 in between the values just listed force applied at roller 11 and air pressure output from regulator 19 are linearly related the reason for the inverted relationship is clear a lower force at roller 11 during this phase of the process implies a faster roof bolt torque decay rate and therefore requires a higher final installation torque the output from regulator 19 is trapped at this stage to serve as reference for the final phase of the installation cycle details of this trapping of the signal are provided below if desired varying relationships between.