front railing on a carriage
軾 refers specifically to the front horizontal railing or bar on a carriage or chariot, used for support or to lean on.
軾 combines 車 (vehicle) with 式, which likely contributes the sound and may relate to a pattern or form, suggesting a structural part of a carriage.
The left side 車 is a vehicle, and the right side 式 looks like a crossbar with a hook. Picture the front railing of a carriage shaped like 式, where the driver can lean forward.
For ショク, imagine a shock-absorbing front railing on a carriage: shock -> ショク, and the railing helps cushion the ride.