Building services and repairs Module 1: Lifts and Escalators Ronny J Dsouza Assistant Professor SJCEM Lifts: Definition : • The lift is a type of vertical transport equipment that moves people or goods between floors of a building and other structures. • As per the National Building Code (NBC) every building having height more than 13 meters needs to have a lift with minimum capacity of carrying six persons. Classification of Lifts: • As per drive system • Traction lifts / Machine lifts • Hydraulic lifts As per their use • Passenger • Goods • Vehicle 1. Traction / Machine lift : • These lifts works on the principle of see- saw. • The car is raised and lowered by traction steel ropes. • One side of the steel rope is attached to the car and other side of rope is attached to an electric motor. • Sometimes other side of the rope is attached to the counterweight, here counterweight and car are perfectly balanced. Fig : traction lift 2. Hydraulic lift: • These lifts work on the “Pascal's Principle” which states that pressure given to liquid on one side will transfer that pressure to another side with uniform and same magnitude. Major components of hydraulic lift: • 1. Tank = It holds the liquid used in the system, liquid used are usually oil based because of its non- compressible nature. • 2. Motor = Pushes oil into the cylinder to lift the elevator car. • 3. Valve = Controls the pressure, when it is open it reduces the pressure whereas when it is closed the pressure increases which raises the car. Special features required for Physically handicapped person: • As per bylaws, provision of atleast one lift shall be made for the wheelchair users, • Cage dimension should be: • clear internal length : 1100mm • clear internal width : 2000mm • entrance door width : 900mm Escalator: Definition of escalator: • It is defined as moving staircase which is used as a transporting device for carrying people between floors of a building. • It is used to move individual up or down on tracks, as well as it has a capacity to move large numbers of people. • In escalator, pair of chains are looped around two pairs of gears and an electric motor runs it. Fig of escalator: Conveyors: Definition: • Conveyors are mechanical devices used to move packages with the help of belt conveyor system. • Conveyors are also called as autowalks, passenger conveyors and moving pavements. • Conveyors can be maximum upto 300m, whereas speed ranges between 0.6 and 1.3 m/s. • Materials of conveyor can be rubber, steel plates, etc; Fig : Conveyor Types of conveyors : • 1. Belt conveyor : Belt conveyors are material handling systems that use continuous belts to convey products or materials. • Belt conveyors can be used to transport products in a straight line or through changes in elevation or direction. For conveying Bulk Materials like Grains, Ore, Coal, Sand etc., over gentle slopes • 2. slat belt conveyor : Slat belt use slats which is made up of steel, wood, typically mounted on roller chains to convey products. • it is mainly used to transfer heavy materials. • 3. Overhead conveyor = Overhead conveyors are mounted from ceilings that use trolleys or carriers which is moved by chains, cables, etc; Motors Function: • The function of a motor is to convert electricial energy into mechanical energy. • There are two categories of motors: • AC motors • DC motors AC motors: • This type of current changes its direction of charge periodically. • In AC current the flow changes direction 120 times in a second.
