For the double$-$pump system shown, what should be the pressure settings of the unloading valve and pressure relief valve under the following conditions:

a$)$ Sheet metal punching operation requires a force of $8000$ N

b$)$ Hydraulic cylinder has a $3\mathrm{.}75$ cm diameter piston and a $1\mathrm{.}25$ cm diameter rod.

c$)$ During rapid extension of the cylinder, a frictional pressure loss of $675$ kPa occurs in the line from the high flow pump to the cap end of the cylinder. During the same time, a $350$ kPa pressure loss occurs in the return line from the rod end of the cylinder to the oil tank. Frictional pressure losses in these lines are negligibly small during the punching operation.

d$)$ Assume that the unloading valve and relief valve pressure settings $($for their full pump flow requirements$)$ should be $50\%$ higher than the pressure required to overcome frictional pressure losses and the cylinder punching load, respectively.