The 08.01.351 main spindle collet closing bell is a precision mechanical wear component designed for Gildemeister DMG Mori GS20 and GM20AC multi-spindle lathes, used in the bar clamping system in the configurations with 9012E bar clamping collet for machining up to 20mm maximum diameter and with 9017E bar clamping collet for machining up to 25mm maximum diameter. Its main function is to slide on sleeve 3160202 and, through its internal working profile, act as a lever on clamping fingers 3101108 in order to generate the pullback of the sleeve and bar clamping draw tube 1501352. This pullback produces the movement required to close the collet on the bar and allows the main spindle group to maintain stable, repeatable holding in line with the machining cycle. In this system, the bell is not merely a cover or containment element but a fundamental kinematic component: it receives and transmits the closing command, controls the contact point with the clamping fingers, converts axial sliding into lever action, contributes to pullback of sleeve 3160202 and enables controlled closure of collets 9012E and 9017E. During the machine cycle, bell 0801351 works in coordination with sleeve 3160202, clamping fingerss 3101108, bushing 3101110, ring 3101107 and draw tube 1501352; every element in the chain must maintain correct geometry, sliding and support so that command force is transmitted without losses, sticking or abnormal play. The quality of the bell internal profile directly affects the regularity of the lever action on the clamping fingers: if the profile is worn, scored, ovalized or no longer uniform, the stroke can become irregular, collet closing force can decrease and opening can become difficult or incomplete. For this reason, the bell is a very important wear component and its replacement often helps solve collet opening problems, inconsistent closure, uncertain return of the system and loss of bar gripping repeatability. From a kinematic point of view, bell 0801351 participates in several functions of the main spindle group: it slides on sleeve 3160202, commands clamping fingers 3101108 through the internal profile, produces the lever effect required for pullback, works together with draw tube 1501352 in collet closure, maintains the functional sequence between clamping group, main spindle and bar feeding system and must remain coordinated with the spindle drum, main spindles, possible front tool spindles, radial slides, axial slides and auxiliary machine systems. An efficient bell helps keep the bar correctly clamped, reducing micro slipping, vibration, loss of concentricity, cutting instability, dimensional errors, form errors and workpiece geometry defects. In the variant with collet 9012E, used for bars up to 20mm, precise and fast closure is essential to preserve cycle stability; in the variant with collet 9017E, used for bars up to 25mm, the higher bar mass and higher loads make the quality of contact between bell, clamping fingers and sleeve even more critical. Over time, the bell may wear on the internal lever surfaces, sliding areas on the sleeve, functional supports and points subject to compression and rubbing. Wear can generate play, sticking, non-linear sliding, loss of useful stroke, reduction of effective closing force and difficulty in collet opening. For this reason, the component must be inspected during preventive and extraordinary maintenance whenever collet opening or closing anomalies occur, during replacement of clamping fingerss 3101108 and during service work on sleeve 3160202 and draw tube 1501352. If wear marks, scoring, deep impressions, deformation, steps or an irregular internal profile are present, replacement of the bell becomes a recommended technical intervention to restore correct command kinematics and full efficiency of bar clamping. For maintenance departments, automatic turning shops, machine tool builders, automotive production and precision engineering, the 08.01.351 collet closing bell is a critical spare part for maintaining reliability, clamping precision and production continuity on Gildemeister DMG Mori GS20 and GM20AC multi-spindle lathes. Tadaah offers this component as a functional part of the main spindle collet closing system, to be assessed not only for dimensional compatibility but also for its kinematic role in sliding, lever action on the clamping fingers, sleeve pullback and controlled closure of the 9012E and 9017E bar clamping collets.