A compensating rope sheave tie-down uses a hydraulic control system comprising various valves to control sheave motion. The sheave is permitted by the control system to move up and down slightly at slow rates, but is held in place if a high rate occurs. The control also permits the sheave to drop down to apply tension to the compensating rope.
A method of providing a durable, long lasting chemically resistant, pH tolerant, corrosion inhibiting film on the surfact of copper or copper containing metal in contact with an aggressive aqueous system is disclosed. The copper or copper containing metal generally composes a structure of dynamic cooling water system, and protection is afforded thereto by intermittently feeding to the aqueous medium a sufficient amount of a C.sub.3 to C.sub.6 alkyl substituted benzotriazole.
Tension of compensating ropes in an elevator system is electively changed to minimize horizontal vibration of the compensating ropes in tall buildings. The tension of compensating ropes is changed by a tensioning mechanism either when the horizontal movement of the compensating ropes exceeds a preset limit or when the building sway exceeds a predetermined amount. Additionally, the tension of compensating ropes can be changed when the elevator car is parked within certain predetermined top floors. The tension can be applied to a compensating sheave supporting the compensating ropes by a tensioning mechanism such as a hydraulic jack.
A trailing rope tensioning device for an elevator installation includes at least one damper having at least one piston slidably received in a cylinder. The piston divides the cylinder into two chambers filled with a working fluid and connected together by a throttled connecting line as well as a channel fitted with a non-return valve. Attached to the piston is a fixed piston rod extending through the cylinder and emerging from ends of the cylinder. This arrangement requires no externally active container for damping.
A controlled tension cable transport system is disclosed, comprising a pulley with fixed axis and a second pulley whose axis occupies a position which is normally fixed during operation. Four sensors measure the tension of the cable during a previous test phase, with the installation off load, and a computing and control assembly compares the measurement results obtained with admissible limit values, for allowing or preventing operation of the installation. Preferably, the computing and control assembly permanently compares the tension of the cable and the torque of the pulley with respect to admissible threshold values during operation of the installation.
A lifting device, for vehicles, has two support platforms. Scissor mechanisms connect these platforms, to bases, and are actuated by hydraulic piston and cylinder assemblies. A combiner and divider valve supplies fluid to the two hydraulic cylinders. A single cross brace can be provided between the two support platforms. This ensures the two platforms operate uniformly, even for an uneven load distribution, while giving a clear working space.
