If it’s a hydraulic gear then your forward clutch
friction pack might be worn. The transmission has a gear pump
. This pump
is in constant use whenever your engine is running. Oil
is pumped through a rotary valve that you control with your shifter. In natural oil bypasses the planetary gear housing that contains the clutch
pack. When placed in forward oil is directed into this housing and the oil pressure (about 140 psi) pushes brass clutch plates or disks against friction plates. These bind together and the torque is transferred to planetary gears and you see the sharp turn. If oil pressure is low (pump failing or low oil level) or the clutches are worn you can expect transmission slipping or other problems. You should if not already have placed a pressure gauge in your transmission oil hose that is between transmission and transmission oil cooler that way you can see your oil pressure. Gauge should be high quality oil filled available at NAPA. Remember this is for a hydraulic transmission not a mechanical gear, these work
differently but it’s doubtful you have a mechanical unless it’s very old.