Sealed bearing rotary cone rock bits that utilize a standard belleville seal oftentimes require that the static side of the seal be secured to a junction formed between a shirttail portion and a journal of a leg of the rock bit. A metal ring on the static side of the belleville seal is secured to the junction between the journal and the shirttail portion of the leg and imposes a load on the inner diameter of an encapsulated belleville spring. By preloading the inner diameter of the belleville spring, the load on the spring continues to increase as the spring is deflected during use. The present invention utilizes an isolated encapsulated belleville spring such that the inner diameter of the belleville spring is not trapped between the metallic ring on the static side of the seal. The result is that as the deflection of the spring is increased under operating conditions, the load reaches a peak value and then begins to decrease. The belleville spring in the isolated state thus can endure large amounts of wear with little or no loss in load or contact pressure.