Overload protection systems Essay Example | Topics and Well Written Essays - 1000 words

Overload protection systems - Essay Example Depending on the type of overload, the appropriate protection systems are chosen and employed is design of machines. For instance, relays, overload release and circuit breakers are used to protect systems against mechanical overload (Bhalja & Maheshwari, 2011). The most common overload protection systems are mechanical and hydraulic overload protection systems. Mechanical overload protection systems are used in mechanical presses; the working principle is based on a delicate shear plate that requires approximately 130% capacity to be broken. When the shear plate is broken, a slide in position has some space of free distance that allows the press to go through a complete stroke. The shear plate is replaced after each case of overload. Hydraulic overload protection systems are more common because the force of the press can be restricted by controlling the hydraulic pressure, and the press can be restarted after an incidence of overload without having to change the plates. Overload prot ection systems (a) mechanical (b) hydraulic (Altan & Tekkaya, 2012). The system consists of an oil pad placed between the slide and the connecting rod to which pressure is applied when force is developing. The pressure from the oil is used to move another piston, which acts to intensify the pressurized air. In case the oil pressure (air pressure) exceeds a threshold value, the oil is sapped back into a tank. Therefore, the force applied is restricted and some space is created for free movement. (Altan & Tekkaya, 2012). a) Torque guard Torque guards are overload protection devices used in power transmission  applications. A spring with a load cam follower placed in a core and detent causes the core and load to rotate jointly. Thus the load always resets in one position and stays in phase when tripped. The system automatically resets when it goes back into the set position after tripping, normally by moving the machine after the overload is cleared. Torque guards assist to protect m echanical systems from damage that may result from extreme torque produced by jamming and overloads. The automatic reset and instant reaction capacity offers consummate guard and reduces down-time. The system disengages at the stipulated torque limit (Grote & Antonsson, 2009). b) Torque limiter A Torque Limiter is a torque overload system consisting of a spring loaded friction style. The load connected to the friction pads is regulated in order to transmit the process torque is transmitted. An overload torque that exceeds the set torque makes the system to slip, preventing overloads from passing through the system. The torque limiter stops slipping when the load drops below the set level, transmitting the torque. In a torque limiter, the phase between input and output is not kept constant. This system can be used in a chain drive with a machined sprocket placed between the friction pads to act as the slip interface so that shutdown and restart is not necessary (Grote & Antonsson, 20 09). Torque limiters are regularly used in applications such as conveyor systems, machine tools, and off-highway mobile equipment. c) Axial guard Axial guards are used in systems where the load acts in the linear rather than revolving direction. This overload protection device provides greatly accurate and repeatable trip point. The point of load set is simply adjusted by rotating a screw. The Axial Guard instantly trips when overload occurs and the tie between the load side and drive side is disengaged. The Axial Guard is reset by a slight push or pull in the reverse direction, allowing production to be revived swiftly and downtime to be reduced (Grote &

Micro economics project about 4 articles (critical analysis) Essay

Micro economics project about 4 articles (critical analysis) - Essay Example These days, however, we’re facing another formidable foe. It’s called real estate. Investors (young and old) have a significant portion of their net worth invested in their homes, and we’re seeing more of them consider adding an income property to their portfolio. I wanted to see what we’re up against, so I put residential real estate through my usual research process. Just as I do with stocks and bonds, I looked at houses and condos from the perspective of economic fundamentals, valuation and market sentiment. Starting with the economics, it would appear the supply side of the equation looks manageable (except maybe condos in Toronto). Housing starts have exceeded household formation for a decade, but the inventory of unsold homes is not excessive. The demand side, however, is less encouraging. What drives real estate over the long term is income growth (i.e. jobs). As Canada becomes less competitive in the global markets and our governments stop prescribing stimulus, employment trends arent too exciting. In the meantime, our home ownership rate has gone from 62 per cent 15 years ago to 70 per cent today, slightly above the level attained in the U.S. in 2006. Still on the demand side, the demographic charts show the segment of the population that’s the strongest net buyer of houses (those aged 25 to 34) is about to start declining, while the pool of potential sellers (over 65) is continuing to increase. The situation is the opposite to what prevailed in the 70’s and 80’s when the early boomers had a huge wave of buyers following behind them. While supply and demand factors are important, what’s really driving real estate these days is financing. Sellers can charge fancy prices when buyers are plugging 2 to 3 per cent into their mortgage calculators. But here too, the trends are worrisome. Rates have little room to drop (despite Bank of Montreal’s efforts) and consumer debt levels are now equivalent to the U.S. at its