-74 4WSR-B & 4WA. -74 4WSR-B and 4WA. Cartridge and Base of the Suspension Strut Assembly. A Shock Absorber is a Device that Controls the Spring oscillations when the Vehicle goes Over various Road irregularities. so the vehicles tires remain in Contact. In some cases. Shock Absorbers have a Secondary function as a Suspension Limiter to prevent the Suspension from either Over. extending and / or Over. compressing.