Depending upon the brand of front axle, there is a cap in top and bottom that should either thread in or is held by a snap ring. These need to be removed. There is then a tapered pin with a nut on one end that is in the middle of the axle. Remove the nut and knock the pin out. Some axles had 2 of these pins but most of them had just one. With this removed the kingpin should then knock out of the axle. Depending on how your equiped you will find it easier to remove the wheel, wheel bearings and hubs. On some units if the hub is left on you might have to knock the pin up through the axle as it will not clear the brake backing plate when knocked out the bottom. The tie rod end could also be removed then when the kingpin is removed the spindle can be removed and bushings replaced. Some bushings will need to be reamed to fit new kingpin, there are some brands that dont require reaming. They can then be installed in reverse order, install shims to take up in up and down slack.
Hope this answers your question,
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