Industrial Hand Pumps come in 3 different flavors:

1. SINGLE SPEED - Delivers a constant flow of oil and pressure to the ram/cylinder. Fine for smaller, shorter travel, single acting spring or gravity return ram/cylinders from about 5 ton up to 30 ton capacity, then your arm starts getting sore...

2. TWO SPEED - Delivers a low pressure but high volume of oil to the ram/cylinder until the load is contacted, then an internal valve switches the pump to deliver a high pressure, lower volume flow of oil while loaded. Best for larger or longer, single-acting, spring or gravity return ram/cylinders. Saves time and physical exertion.

3. TWO SPEED w/4 WAY VALVE - Same attributes as above (#2) but the 4 Way Valve is necessary to operate double acting, push/pull ram/cylinders.