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		Feather Key Joints - Course: Techniques of fitting and assembling component parts to produce simple units. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 19 p.)
			(introduction...)
			Introduction
			Hints on Labour Safety
			1. Purpose of Feather Key Joints
			2. Kinds of Feather Keys and Profile Shafts
			3. Kinds of Feather Key Joints
			4. Stress on the Feather Key Joints
			5. Tools, Devices and Auxiliary Means
			6. Technological Processes for Manufacturing Feather Key Joints and Profile Shaft Joints
			7. Detachment of Feather Key Joints

7. Detachment of Feather Key Joints

Parts of machines, which shall be dismantled and reassembled after maintenance or repair, have to be marked before dismantling. This will help to reassemble them correctly.

7.1. Detachment of Shaft and Hub

If there is a clearance fit between shaft and hub, the parts can be separated by hand power, if the external locking elements, such as shaft snap rings and retainer rings, had been removed before.

With transition and interference fits between shaft and hub, the parts must de drawn apart by a suitable puller.

With smaller units also presses may be used.

With very tight interference fits between shaft and hub, the hub must be thoroughly heated within a short time.

Short, systematic hammer blows must be done directly against the shaft journal, then the puller is applied, the screw is actuated and the hub is drawn off.

Figure 26 Detachment of shaft and hub by the puller

7.2. Detachment of Feather Key from the Keyway of the Shaft

Feather keys without locking screws often stick in the keyway of the shaft very tightly, because they are held by the tight fit and the oil.

They must be gripped by suitable adjustable pliers and lifted in vertical direction. If the spring sticks in the keyway very tightly, careful hammer blows in connection with a non-ferrous metal drift pin will enable the loosening of the spring in the keyway. The hammer blows must be done in axial direction only. With ending keyways, the key may be pushed towards the end of the shaft. If the key is fastened by retaining screws, these must be unscrewed first. Then, the key can be taken out. Keys that have a tapped hole for a forcing screw are easy to remove out of the keyway:

A suitable screw with a long stud is screwed into the bore hole. The stud, while being turned, exercises pressure against the keyway of the shaft thus lifting the key upwards.

Figure 27 Detachment of the key from the keyway of the shaft by forcing screw and screw driver

How is a fitting key joint detached, if there is an interference fit between shaft and hub?
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