Load data is found in the deliveries. There are four fields that refer to different load states :
planned_loads returns the list of loads that were entered in Dashdoc before loading has started.
origin_loads returns the list of loads at loading.
destination_loads returns the lis tof loads at unloading.
loads returns the "latest" loads (= planned_loads if loading hasn't started, =origin_loads if loading is done but not unloading, = destination_loads if delivery is complete)
All these fields contain much data about the loads (e.g. weight, description etc.) This is all described in the API reference.