Abstract: A lifting machine with a counterweight includes a sensing system for assisting in ensuring proper operating conditions are reliably achieved. The machine includes a lifter for moving the counterweight from a lowered position to a raised position. A first sensor is associated with the lifter for sensing a parameter corresponding to an amount of the counterweight (such as a pressure value associated with the rod end of a lifting cylinder), and a second sensor is provided for sensing a condition of the lifter (such as the position or extended length of the lifting cylinder). The amount of counterweight present may be determined by the output of the first sensor when the lifter is in a pre-determined (e.g., midpoint) position. The operator may be polled to verify the amount of counterweight present, thus providing a check against unintended operating conditions and ensure that reliable operation of the lifting machine is achieved.