A double toggle jaw crusher is much larger, heavier, more moving parts and lower throughput than modern single toggle jaw crushers. The lower throughput statement is a bit misleading because it’s partially attributed to the type of bearings they have versus modern crushers, so if one was to upgrade the bearings, throughput could be closer to that of a modern jaw.
Anyway, double toggle jaw crushes are really more about where the eccentric is located than anything. In a double toggle jaw crusher, the eccentric is located behind the swinging jaw. This has two main effects, – it keeps the eccentric out of harms way because there is no shock loading from the rock being crushed being transferred to the eccentric shaft and bearings. The other effect is a limited plane of motion for the swinging jaw which contributes to its lack of productivity. The jaw moves like a swinging door that is hinged at the top and is being pushed open and pulled closed at the bottom. One toggle plate goes from the bottom of the eccentric arm to the bottom of the swinging jaw, the other toggle plate goes from the opposite side of the bottom of the eccentric arm to a fixed point at the very back of the jaw crusher frame.
Single Toggle Jaw Crusher
Double Toggle Jaw Crusher
In contrast, the single toggle jaw crusher has fewer shafts and bearings and only one toggle which goes from the bottom of the swinging jaw to a fixed point at the back of the jaw crusher. The eccentric is located at the top of the swinging jaw and is part of the shaft. The advantage of this is that the jaw has two motions that are happening at the same time. It has the same swinging door motion that the double toggle has, but also has the up and down motion from the eccentric.