Machine Parts

Types of Feed Gearboxes a.       Feed gearbox with sleep gears :  One of its advantages is the small axial dimension. It is possible to design for a large number of feed rates, if kept within the limits of the upper and the lower transmission ratios. Such gearboxes are used, where feed changes are less frequent. The machines are automatic, semi automatic, special purpose and single purpose machine tools. b.       Feed gearbox with slip gear quadrants : Slip gear fitted to shaft having fixed center distance does not give very accurate output speed. It here have a large number of very finely stepped spindle speeds is required and the actual speeds are to be very accurate. The arrangement of the slip gear is changed. Between the fixed axes of the driving shaft and the driven shaft is placed on a carrier. The intermediate shaft can be adjusted by its linear displacement along the slot in the quardant by swiveling it round axis.                   

A Number of gears is placed on the one shaft which is at fixed distance from the output shaft. The transmission takes placed over another gear which can be swung backand forth for proper meshing with the driving and driven gears. The system is usually used for feed drives and also known as Norton gear box. Sliding Types Cluster Gears: A set of cluster gears where two or three gears is moved along a shaft to engage another set of gears where one gear of the cluster is engaged at a time. An advantageous application of positive clutches is the back gear arrangement . Both the driving and the driven shafts are placed co-axially so that either they coupled directly ot indirectly over a number of intermediate gears.  Friction Clutches: Friction Clutches permits rapid and smooth speed changing without stopping the machine and the use of helical and herringbone gears in a gearbox. The limiting torque capacity, high friction loss and comparatively large axial

  A fixture for production machining must be considered like any other machine tool. It should pay for itself from the savings derived from its used. The tool designer may be required to designer the cost of a fixture and whether its construction will be profitable in the early stages of fixture design. The cost and return can not be determined exactly because of the variables that may enter into the overall picture, but a close estimate can be made from formulas developed for this purpose.   The economic aspects of the use of a fixture can be considered of the following basic: 1.       The production per year necessary to pay out of savings for a fixture of given estimated cost. 2.       The maximum allowable cost of a fixture to break even for a given saving in operating cost per price and specific cost given yearly production. 3.       The number of years will take to pay out of savings for the proposed fixture with given savings operating cost per price an