Abstract: An anti-two block system for a crane having a body formed of a first plate and a second plate, a weighted member connected to the second plate of the body so as to contact a travelling member of the crane when the travelling member moves upwardly beyond a desired level, and a valve affixed to the first plate of the body. The valve is movable between a first position closing the valve and a second position opening the valve. The valve serves to pass fluid flow therethrough in response to a contact between the travelling member and the weighted member. The first plate is connected to the second plate. A spring is interactively connected between the plates so as to urge the second plate upwardly along the first plate when the travelling member contacts the weighted member. The weighted member has a weight so as to overcome the resistance of the spring such that the valve resides in the first position in the absence of contact between the weighted member and the travelling member.

Abstract: A load block having a body, a sheave rotatably positioned within the body, and a hook having a shank received within the body and having a portion positioned in a generally air-tight volume within the body. The body includes a first side plate, a second side plate in generally parallel relationship to the first side plate, and a crossblock affixed to and extending between the first and second side plates. The air-tight volume is formed within the crossblock. The crossblock includes a cover which is affixed to a top surface of the crossblock and is in generally liquid-tight relationship to the crossblock. A liquid fills the volume of the crossblock so as to extend around a portion of the shank. The cover has a check valve positioned on a surface for allowing air to pass from the volume and for preventing air from passing into the volume. The sheave includes an inner race around a bearing assembly adjacent to a shaft formed in the body. A pair of dead-eyes are positioned on opposite sides of the body.