In a large crushing scenario, the capacity of the primary crusher is vital to the continuous crushing of the system. To overcome shortfalls in capacity, Lippmann engineers have designed removable hopper extensions that can be mounted to any custom portable plant. These extensions allow for larger buckets to be used while feeding material and can increase capacity by 50%. In truly enormous applications, Lippmann has designed rock box structures that permit portable jaw plants to dock directly below the structure. Rock boxes allow for multiple dumps into the system without interrupting the crushing circuit.