General Principles
Nomenclature

	Contact pressure	p	in	N/mm2
	Axial ring width	h	in	mm
	Bending moment	M	in	N/mm
	Diametral force	Fd	in	N
	Closure stress	σb	in	N/mm2
	Modulus of elasticity	E	in	N/mm2
	Spring force		in	N
	Conformability	U	in	mm
	Gas pressure	pz	in	N/mm2
	Piston ring parameter	k		-
	Radius of curvature of the open ring (ring in free state)	ρ1	in	mm
	Radius of curvature of the closed ring (ring at nominal diameter)	ρ2	in	mm
	Inertia force		in	N
	Total free gap	m	in	mm
	Nominal diameter	d	in	mm
	Ovality	u	in	mm
	Radial wall thickness	a	in	mm
	Radius at outside diameter	r	in	mm
	Radius of ring centre line	rm	in	mm
	Friction force		in	N
	Closed gap	s	in	mm
	Tangential force	Ft	in	N
	Moment of inertia	l	in	mm4
	Assembly stress: tangential opening	σbüT	in	N/mm2
	Assembly stress: opening by means of a sleeve	σbüH	in	N/mm2