HST products in APAC Market

Jasper Li

Regional Sales Manager at Hydro-Gear

领英：https://cn.linkedin.com/in/jasper-li-7b438039/zh-cn

HST–Hydrostatic Transmission, broadly speaking, it is the system consisting of pump and motor in closed-loop hydraulic system, 

If it means some special product in hydraulic field, it means the device including one piston pump and one piston motor in one housing to make up one whole closed-loop system, it's a component in drive system of off-high-way mobile machine, the device function is more like hydrodynamic coupling, but with much more converting efficiency at low wide speed range (generally, the HST works at 500~3500rpm)

Because of its high reliability, and cost-effective for drive system, in APAC, it’s widely used in Agricultural machine and road service machine.

HST pump is variable displacement pump, the HST motor generally is fixed displacement motor, for one HST, pump max displacement is as same as the motor's, that means HST only performs stepless speed regulation (0~max speed) ,  do not enlarge output torque.

Currently, HST displacement ranges from 5cc~52cc, only applied on the vehicles whose power cover 5.5hp~100hp.

It’s could not be too small, because for small vehicles, customer prefer Mechanical Transmission to HST, because of small HST’s price is much higher than  MT,

 it's could not be too large, because the large HST could produce more heat than it could emit, and output torque of large HST is too heavy to transfer to next stage, if drive chain need more power, HST manufacturers incline to recommend individual pump and motor system.

Because HST is customized integrated product in a way, its target market is high volume application to reduce the average cost on each product. 

Most important advantage of HST is stepless speed control, which makes it easier to maneuver vehicle. 

In US and EU, many years ago the biggest market of HST is riding mower market (Zero Turn Rider and Lawn Tractor, over 1 million sets per year), it's the small HST market(10cc&21cc), but HST suppliers have combined HST and gear transaxle together, fostering one Hydrostatic Transaxle market, so the demand of pure HST have vanished nearly.

US is a heavy-duty machine market, so it's a big-pump-bi- motor market, not HST's.

EU have numerous applications fitting for HST, but the demand quantity of each application is low, and there are a lot of strong pump&motor manufacturers  in EU, so there is a few applications going with HST.

Japan have developed a lot medium-sized vehicles which fit for working in compact places: agricultural combine, mini excavator, carrier, and volume is very high, so Japanese find that HST is the economical and reliable solutions for some applications, it's Japanese who further develop HST products, the applications focus on agricultural machines: rice combine, rice trans planter, agricultural carrier, HST compact tractor, heavy duty snow blower…

With Korea and China economy rising, Korean and Chinese follow Japanese steps to make HSTs, now every HST brands has been in China to share the bonus of China Agricultural machine market.

Following diagram shows the HST brands and their displacements distribution.

The number in black color (displacement) is shoeless piston HST, displacement is less than 23cc, and max pressure is 240bar, applied on the vehicle whose power could reach 25hp max.

the number in red color(displacement) is shoe piston HST, displacement is from 23cc~52cc, max pressure could reach 350bar, applied on the vehicle powering to 100hp

Danfoss HST is coming from Daikin and Hydro-Gear, Daikin in Japan supplies  full line of HST for Kubota, Mitsubishi , TYM, Hydro-Gear only supply small HST for some light vehicles.

Kanzaki only basically supply HSTs for its parent company Yanmar in Japan.

KYB supply HST for Iseki, and who have a lot of other applications.

Danfoss (Daikin, Hydro-Gear), Kanzaki and KYB is the first level in the Market, they are very strong in market, they all have full product line to cover all HST applications, but in China,  high price and long response time is their weakness, because Danfoss and Kanzaki have had big Japanese partner using their products in China, they are not so active for domestic OEMs in market, they are more like information collectors, KYB is more positive in China, the brand has developed a lot new customers in China.

Korean developed HST a couple years earlier than Chinese, so Korean have accumulated some technology on HST, and they keep in step with Japanese, and have full line, too.

Jeil and JI YHD traditionally make pump and motor products in after-service market, with the market demand in Korea and China, they shifted to make HST products.

Chinese history making HST is short

 Liyuan Hydaulic is first manufacturer to make HST for rice combine market, with several year development, they supply over 60% HST in China (total market is about 70,000) now

99% HST in China are applied in agricultural market(rice combine), with the market growing, many domestic hydraulic parts suppliers turned to make the products, for example, High-Tech is a pump supplier, Jindun is supplier of fork lift hydraulic parts,

Every HST supplier manages to get more share percentage in the market. Japanese brands are trying to defend their sharing in the market, Korean and Chinese local suppliers are more flexible to meet customer requests to catch local demands;  Korean guy needs big OEMs to set up their fame in market, Chinese need improve products PPM to reduce customers' complaint.

Generally for HST, the input shaft is parallel with output shaft, if input shaft and output shaft are located at the same side of HST, it's U style HST such High-Tech HT series, if they are located at different two sides, we call Z style HST, such as Danfoss BDU-10.

Because some special installation request, the input shaft and output shaft should be at right angle, such as Hydro-Gear RT-310 and BDR products.  This type of HST has internal hydraulic reduction because motor displacement is bigger than pump's,

For Eaton Model 6/7/11 products, input shaft and output shaft is at the same central line, looks like a coupling, in fact it's a combination of one radial ball piston pump and one radial ball piston motor.

When a constant rpm drives HST input shaft, the output shaft speed is control by pump swash plate angle, what mechanism drives the swash plate?

Generally, below 32cc HST, there is a trunnion arm directly driving the pump swash plate, we call it DDC control (Direct Displacement Control), such as Danfoss BDU-10.

 If the displacement is bigger than 32cc, there is a pilot oil to push the swash plate, original signal is put by manual, and we call MDC (Manual Displacement Control), such as High-Tech HT series.

Because HST is standard closed-loop system, so there are many applications in the World, according to HST annual consumption in recent 3 years, application includes: 

Rice Combine (100,000 sets), 

HST Compact tractor (unknown) 

Trans planter (30,000 sets),

 Road roller (2,000 sets), 

Road Line striper (2,000 sets),

Sweeper, commercial lawn mower, sprayer, tracked carrier and so on.

排版编辑：马艳双

关于iHydrostatics

iHydrostatics, Pulse You with World