Device for inserting sheets into envelopes

A sheet insertion device for inserting sheets into envelopes, the device comprising:

• a fixed insertion station per se, fed with empty envelopes which are separate from one another;
• a fixed sheet inlet station including a fixed inlet tray, said station being at a distance from the insertion station and being fed with sheets which are separate from one another;
• a sheet transfer and insertion tray referred to as a "carriage" which is driven in translation along a "go" stroke from a first position in which it is retracted beneath the fixed inlet tray to a second position in which it is at least partially engaged in the envelope present in the insertion station, and also along an opposite "return" stroke, said carriage being fixed with pusher fingers having forwardlydirected sheet grasping means for grasping the sheet present in the inlet station, said fingers projecting above the level of the inlet station in order to retain the sheet by their grasping means and to push it during said go stroke, wherein said pusher fingers and said forwardly-directed sheet grasping means are fixed relative to each other and are fixed relative to the carriage, with said forwardly-directed grasping means projecting just above the level of the inlet station in order to leave them free to pass beneath a sheet waiting in the inlet station during the return stroke of the carriage, and wherein the sheet insertion device further includes holding-down fingers mounted above the inlet station and controlled to take up a holding-down position against the inlet station at least during the beginning of said carriage go stroke in order to force the sheet beneath said grasping means, thereby ensuring that the sheet is taken by said grasping means of each pulser finger, and also having a retracted position above the inlet station during the remainder of the go stroke and during the return stroke of the carriage in order to leave the inlet station free to be fed with a new sheet.